View Filing Data

Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2018	Oct. 30, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q3
Trading Symbol	CORT
Entity Registrant Name	CORCEPT THERAPEUTICS INC
Entity Central Index Key	0001088856
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		115,471,798

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 33,894	$ 31,062
Short-term marketable securities	161,300	57,682
Trade receivables, net of allowances	19,360	15,300
Other receivable	0	12,896
Inventory	5,362	4,576
Prepaid expenses and other current assets	4,275	2,669
Total current assets	224,191	124,185
Strategic inventory	7,360	3,800
Property and equipment, net of accumulated depreciation	540	518
Long-term marketable securities	1,481	15,281
Other assets	53	50
Deferred tax assets, net	66,126	76,703
Total assets	299,751	220,537
Current liabilities:
Accounts payable	13,922	8,579
Accrued clinical expenses	5,392	2,247
Other accrued liabilities	20,892	18,743
Total current liabilities	40,206	29,569
Commitments and contingencies (Note 5)
Stockholders’ equity:
Preferred stock
Common stock	116	115
Additional paid-in capital	408,154	384,074
Treasury stock	(8,904)
Accumulated other comprehensive loss	(77)	(75)
Accumulated deficit	(139,744)	(193,146)
Total stockholders’ equity	259,545	190,968
Total liabilities and stockholders’ equity	$ 299,751	$ 220,537

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement Of Income And Comprehensive Income [Abstract]
Product revenue, net	$ 64,445	$ 42,763	$ 184,416	$ 105,921
Type of Revenue [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember
Operating expenses:
Cost of sales	$ 1,308	$ 976	$ 3,636	$ 2,397
Type of Cost, Good or Service [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember
Research and development	$ 18,860	$ 11,693	$ 56,453	$ 26,745
Selling, general and administrative	21,308	16,471	59,729	45,621
Total operating expenses	41,476	29,140	119,818	74,763
Income from operations	22,969	13,623	64,598	31,158
Interest and other income (expense)	759	86	1,615	(237)
Income before income taxes	23,728	13,709	66,213	30,921
Income tax (expense) benefit	(5,981)	48	(12,811)	(129)
Net income	17,747	13,757	53,402	30,792
Other comprehensive income (loss):
Net unrealized income (loss) on available-for-sale investments, net of tax impact of $(16), $0, $25 and $0, respectively	50	3	(77)	(14)
Total comprehensive income	$ 17,797	$ 13,760	$ 53,325	$ 30,778
Basic net income per share	$ 0.15	$ 0.12	$ 0.46	$ 0.27
Diluted net income per share	$ 0.14	$ 0.11	$ 0.42	$ 0.25
Weighted-average shares outstanding used in computing net income per share
Basic	115,798	113,603	115,394	113,242
Diluted	126,159	125,651	127,167	123,417

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net unrealized income (loss) on available-for-sale investments, tax impact	$ (16,000)	$ 0	$ 25,000	$ 0	$ 0

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities:
Net income	$ 53,402	$ 30,792
Adjustments to reconcile net income to net cash generated from operations:
Stock-based compensation	17,481	9,529
Deferred income taxes	10,602	0
Accretion of interest (income) expense	(1,020)	456
Amortization of debt financing costs	0	14
Depreciation and amortization of property and equipment	163	58
Changes in operating assets and liabilities:
Trade receivables	(4,060)	(2,012)
Other receivable	12,896	(12,965)
Inventory	(4,346)	(344)
Prepaid expenses and other current assets	(1,606)	(1,122)
Other assets	(3)	0
Accounts payable	5,343	3,922
Accrued clinical expenses	3,145	425
Other accrued liabilities	2,149	7,299
Net cash provided by operating activities	94,146	36,052
Cash flows from investing activities:
Purchases of property and equipment	(185)	(390)
Proceeds from maturities of marketable securities	88,500	12,474
Purchases of marketable securities	(177,325)	(58,092)
Cash used in investing activities	(89,010)	(46,008)
Cash flows from financing activities:
Proceeds from issuance of common stock upon exercise of options, net of issuance costs	6,600	4,614
Repurchase of common stock	(8,904)	0
Payments related to debt obligation	0	(15,134)
Net cash used in financing activities	(2,304)	(10,520)
Net increase (decrease) in cash and cash equivalents	2,832	(20,476)
Cash and cash equivalents, at beginning of period	31,062	51,536
Cash and cash equivalents, at end of period	$ 33,894	$ 31,060

Basis of Presentation and Summary of Significant Accounting Policies

9 Months Ended

Sep. 30, 2018

Accounting Policies [Abstract]

Basis of Presentation and Summary of Significant Accounting Policies

1. Basis of Presentation and Summary of Significant Accounting Policies

Description of Business and Basis of Presentation

Corcept Therapeutics Incorporated was incorporated in the State of Delaware in May 1998, and our headquarters are located in Menlo Park, California. We are a pharmaceutical company engaged in the discovery, development and commercialization of medications that treat severe metabolic, oncologic and psychiatric disorders by modulating the effect of the stress hormone cortisol. In 2012, the United States Food and Drug Administration (“FDA”) approved our first product, Korlym^® (“mifepristone”) 300 mg tablets, as a once-daily oral medication for treatment of hyperglycemia secondary to hypercortisolism in adult patients with endogenous Cushing’s syndrome who have type 2 diabetes mellitus or glucose intolerance and have failed surgery or are not candidates for surgery. We have discovered and patented three structurally distinct series of selective cortisol modulators, consisting of more than 500 compounds and are developing compounds from these series to treat a broad range of disorders.

Basis of Presentation

We have prepared the September 30, 2018 balance sheet and statements of comprehensive income and cash flows for the three and nine months ended September 30, 2018 and 2017 in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. They do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments considered necessary for a fair presentation (which in the applicable periods consist only of normal, recurring adjustments) have been included. Operating results for the three and nine months ended September 30, 2018 are not necessarily indicative of the results to expect for the remainder of 2018 or any other period. These financial statements and notes should be read in conjunction with the financial statements for the year ended December 31, 2017 included in our Annual Report on Form 10-K. The December 31, 2017 balance sheet was derived from audited financial statements at that date.

Principles of Consolidation

Our financial statements include the financial position and results of operations of Corcept Therapeutics UK Limited, our wholly owned subsidiary, which we incorporated in the United Kingdom in March 2017. This entity has entered into no material financial transactions and has no assets or liabilities.

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ materially from those estimates.

We reevaluate our estimates and assumptions each quarter, including those related to revenue recognition, recognition and measurement of income tax assets and liabilities, inventory, allowances for doubtful accounts and other accrued liabilities, including our bonus accrual, clinical trial accruals and stock-based compensation.

Fair Value Measurements

We value financial instruments using assumptions we believe third-party market participants would use. When choosing which assumptions to rely upon when determining the value of a financial instrument, we look first for quoted prices in active markets for identical instruments (“Level 1 inputs”). If no Level 1 inputs are available, we consider (i) quoted prices in non-active markets for identical instruments; (ii) active markets for similar instruments; (iii) inputs other than quoted prices for the instrument; and (iv) inputs that are not directly observable, but that are corroborated by observable data (“Level 2 inputs”). In the absence of Level 2 inputs, we rely on unobservable inputs, such as our estimates of the assumptions market participants would use in pricing the instrument (“Level 3 inputs”).

Cash and Cash Equivalents and Marketable Securities

We consider highly liquid investments purchased with original maturities of three months or less from the date of purchase to be cash equivalents. Cash equivalents are valued using Level 1 inputs, which approximate our cost.

We invest a portion of our funds in marketable securities, primarily U.S. Treasury securities, commercial paper, corporate notes, asset-backed securities and repurchase agreements. We classify our marketable securities as available-for-sale securities and report them at fair value as “cash equivalents” or “marketable securities” on our balance sheet, with related unrealized gains and losses included in stockholders' equity. Realized gains and losses and permanent declines in value are included in “interest and other income (expense)” on our statement of comprehensive income.

Concentration of Credit Risk

We are subject to credit risk from our cash equivalents and marketable securities. We limit our investments to U.S. Treasury obligations and high-grade corporate debt, asset-backed securities and repurchase agreements with less than a 36-month maturity at the time of purchase. These investments are diversified and do not expose us to concentrations of credit risk.

Inventory and Cost of Sales

Regulatory approval of product candidates is uncertain. Because product manufactured prior to regulatory approval may not be sold unless regulatory approval is obtained, we record the cost of manufacturing our product candidates as research and development expenses at the time such costs are incurred. We capitalize to inventory manufacturing costs related to Korlym.

We value inventory at the lower of cost or net realizable value and determine the cost of inventory we sell using the specific identification method, which approximates a first-in, first-out basis. We write down inventory that has become obsolete or has a cost basis in excess of its expected net realizable value. Any expired inventory is destroyed and the related costs are recognized as cost of sales in the statement of comprehensive income in that period.

Cost of sales includes the cost of manufacturing Korlym, including materials, third-party manufacturing costs and indirect personnel and other overhead costs, based on the number of Korlym tablets for which we recognize revenue, as well as costs of stability testing, logistics and distribution.

We classify inventory we do not expect to sell or use in clinical studies within 12 months of the balance sheet date as strategic inventory, a noncurrent asset.

Debt Obligation

Under an agreement with Biopharma (the “Biopharma Financing Agreement” or the “Financing Agreement”), we made payments each quarter equal to 20 percent of our Korlym sales in the quarter. Accounting for the Financing Agreement required us to estimate the amount of each future quarterly payment and the accretion of interest expense. We extinguished our obligations under the Financing Agreement in July 2017. No further payments are due.

Revenue

We sell Korlym directly to patients through a single specialty pharmacy. We also sell Korlym to a specialty distributor (“SD”), for which we recognize revenue at the time the SD receives Korlym. SD sales were less than or equal to one percent of our net revenue in each of the three and nine months ended September 30, 2018.

To determine our revenue from the sale of Korlym, we (i) identify our contract with each customer; (ii) identify the obligations of Corcept and the customer under the contract; (iii) determine the contracted transaction price; (iv) allocate the transaction price to the contract’s performance obligations, which in our case consists of delivering Korlym to the customer; and (v) recognize revenue once Korlym has been delivered, provided we deem it probable that we will collect the payment due to us.

Confirmation of coverage by private or government insurance or by a third-party charity is a prerequisite for selling Korlym to a patient.

To determine net product revenue, we deduct from sales the cost of our patient co-pay assistance program and our estimates of (a) government chargebacks and rebates, (b) discounts provided to our SD for prompt payment and (c) reserves for expected Korlym returns. We record these estimates at the time we recognize revenue and update them as new information becomes available. Our estimates take into account our understanding, based on our experience, of the range of possible outcomes. If results differ from our estimates, we adjust our estimates, causing a change to our net product revenue and earnings. We report any changes in the period they become known, even if they concern transactions occurring in prior periods.

Government Rebates: Korlym is eligible for purchase by, or qualifies for reimbursement from, Medicaid and other government programs that are eligible for rebates on the price they pay for Korlym. To determine the appropriate amount to reserve against these rebates, we identify Korlym sold to patients covered by government-funded programs, apply the applicable government discount to these sales, then estimate, based on our experience, the portion of total rebates we expect will be claimed. We then (i) deduct this reserve from revenue in the period to which the rebates relate and (ii) include in accrued expenses on our consolidated balance sheet a current liability of equal amount.

Chargebacks. Although we sell Korlym to the SD at full price, some of the government entities to which the SD sells receive a discount. The SD recovers such discounts by reducing its payment to us (this reduction is called a “chargeback”). Chargebacks sometimes relate to Korlym sold to SD in prior periods. We deduct from our revenue in each period chargebacks claimed by the SD for Korlym we sold to the SD that period. We also create a reserve for chargebacks we estimate the SD will claim in future periods against Korlym it purchased in the current period but has not yet resold. We determine the amount of this reserve based on our experience with SD chargebacks and our understanding of the SD’s customer base and business practices. We then deduct this reserve from revenue and include in accrued expenses on our consolidated balance sheet a current liability of equal amount.

Patient Assistance Program and Charitable Support: It is our policy that no patient be denied Korlym due to inability to pay. We provide financial assistance to eligible patients whose insurance policies have high deductibles or co-payments and deduct the amount of such assistance from gross revenue. We determine the assistance we provide each patient by applying our program guidelines to that patient’s financial position and their insurance policy’s co-payment and deductible requirements for the purchase of Korlym. We donate cash to charities that help patients with financial need pay for the treatment of Cushing’s syndrome. We do not include payments from these charities in revenue. We provide Korlym at no cost to patients without insurance who do not qualify for charitable support.

Sales Returns: Federal law prohibits the return of Korlym sold to patients. Sales to our SD are subject to return. We deduct the amount of Korlym we estimate the SD will return from each period’s gross revenue. We base our estimates on quantitative and qualitative information including, but not limited to, historical return rates, the amount of Korlym held by the SD and projected demand. If we cannot reasonably estimate returns with respect to a particular sale, we defer recognition of revenue until we can make a reasonable estimate. To date, returns have been insignificant.

The following table summarizes activity in each of the product revenue allowance and reserve categories for the nine months ended September 30, 2018.

	Chargebacks			Government Rebates			Total
	(in thousands)
Balance at December 31, 2017:	$	927		$	7,961		$	8,888
Provision related to current period sales		2,539			21,668			24,207
Provision related to prior period sales		—			181			181
Credit or payments made during the period		(2,163	)		(18,653	)		(20,816	)
Balance at September 30, 2018:	$	1,303		$	11,157		$	12,460

Research and Development

Research and development expenses include the direct cost of discovering and screening new compounds, pre-clinical studies, clinical trials, manufacturing development, submissions to regulatory agencies and related overhead costs. We expense nonrefundable payments and the cost of technologies and materials used in research and development as we incur them.

We base our accruals for discovery research, preclinical studies and clinical trials on our estimates of work completed, milestones achieved, patient enrollment and past experience with similar activities. Our estimates include assessments of information from contract research organizations and the status of our own research, development and administrative activities.

Segment Reporting

We determine our operating segments based on the way we organize our business, make decisions and assess performance. We have only one operating segment, which is the discovery, development and commercialization of pharmaceutical products.

Stock-Based Compensation

We account for stock-based compensation under the fair value method, based on the value of the award at the grant date. To date, our stock-based compensation has consisted entirely of option grants, which we value using the Black-Scholes model. We recognize stock-based compensation expense over the applicable vesting period, net of estimated forfeitures. If actual forfeitures differ from our estimates, we adjust stock-based compensation expense accordingly.

We recognize the expense of options granted to non-employees based on their fair value at the time of vesting.

Recently Adopted Accounting Pronouncements

In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, “Revenue from Contracts with Customers,” which changes the way companies recognize revenue. This ASU supersedes the revenue recognition requirements in ASC Topic 605, Revenue Recognition and creates a new Topic 606, “Revenue from Contracts with Customers.” Topic 606 applies to all contracts with customers.

We conducted our analysis using the “portfolio of contracts” approach, which permits us to analyze as a group all contracts with similar characteristics. We have two customer groups: patients covered by insurance and the SD. We evaluated the contracts with customers governing our sales and reviewed the related disclosures, policies and controls, which we updated as necessary. Because some of our customer contracts are subject to rebates, chargebacks, discounts, co-pay assistance or other deductions (known as “variable consideration”) that affect the price of each transaction, we focused our analysis on the new standard’s impact on transaction prices. We estimated the amount of variable consideration using either the most likely amount or expected value method, as applicable.

Topic 606 requires us to estimate the net price of each Korlym sale, including any variable consideration, and recognize the estimated amount as revenue at the time we deliver Korlym to the customer. On January 1, 2018, we adopted Topic 606 using the modified retrospective approach. Adoption of this standard had no impact on our financial statements.

In January 2016, the FASB issued Accounting Standards Update No. 2016-01 “Financial Instruments: Recognition and Measurement of Financial Assets and Financial Liabilities.” This update changes accounting for equity investments, financial liabilities under the fair value option, and the presentation and disclosure requirements for financial instruments. In addition, it clarifies guidance regarding recognition of deferred tax assets that result from unrealized losses on available-for-sale debt securities. We adopted this standard on January 1, 2018. It had no impact on our financial statements.

In August 2016, the FASB issued ASU No. 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments,” which is intended to reduce the existing diversity in practice in how certain cash receipts and cash payments are classified in the statement of cash flows. In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows, Restricted Cash (Topic 230) (ASU 2016-18), which requires the inclusion of restricted cash with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. ASU 2016-15 and ASU 2016-18 are both effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years, provided that all of the amendments are adopted in the same period. We adopted this standard on January 1, 2018. It had no impact on our financial statements.

In May 2017, the FASB issued ASU No. 2017-09, Stock Compensation (Topic 718): “Scope of Modification Accounting,” which changes the accounting for modifications to the terms and conditions of share-based payment awards. We adopted this standard on January 1, 2018. It had no impact on our financial statements.

Recently Issued Accounting Pronouncements Not Yet Adopted

In February 2016, the FASB issued ASU No. 2016-02, “Leases”, which requires lease transactions with terms longer than 12 months to be recognized on the balance sheet as “lease liabilities” and “right-of-use assets.” We plan to adopt this new standard using the modified retrospective approach on January 1, 2019. We have reviewed substantially all contracts that may contain leases and are reviewing our related disclosures, policies and controls, which we will change as required when we adopt the standard. Although our analysis is not yet complete, we believe the new standard’s most significant impact will be to our accounting for our leased office space. We expect that adoption will increase our “lease liabilities” and “right-of-use assets” equally.

In June 2016, the FASB issued ASU No. 2016-13, “Financial Instruments—Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments,” which changes the methodology for measuring credit losses on financial instruments and when such losses are recorded. This standard is effective for fiscal years, and interim periods within those years, beginning after December 15, 2019. Early adoption is permitted beginning after December 15, 2018. We plan to adopt this standard on January 1, 2020. Although we have not concluded our analysis, we do not expect adoption of this standard to have a material impact on our consolidated financial statements.

In February 2018, the FASB issued ASU No. 2018-02, “Income Statement – Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income.” The standard allows companies to reclassify to retained earnings tax effects related to items that have been stranded in accumulated other comprehensive income as a result of the Tax Cuts and Jobs Act (the “Act”). An entity that elects to reclassify these amounts must reclassify stranded tax effects related to the Act’s change in US federal tax rate for all items accounted for in other comprehensive income. These entities can also elect to reclassify other stranded effects that relate to the Act but do not directly relate to the change in the federal rate. This standard is effective for fiscal years, and interim periods within those years, beginning after December 15, 2018. We plan to adopt this standard on January 1, 2019. Although we have not concluded our analysis, we do not expect adoption of this standard to have a material impact on our consolidated financial statements.

In June 2018, the FASB issued ASU No. 2018-07, “Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting,” which expands the scope of ASC 718 to include all share-based payment arrangements related to the acquisition of goods and services from nonemployees. This standard is effective for fiscal years and interim periods within those years, beginning after December 15, 2018. We plan to adopt this new standard on January 1, 2019. Although we have not concluded our evaluation, we do not expect its adoption to have a material impact on our consolidated financial statements.

In August 2018, the FASB issued ASU No. 2018-13, “Fair Value Measurements (Topic 820),” which eliminates or modifies certain disclosure requirements for fair value measurements and requires disclosure of certain new information. This standard is effective for fiscal years, and interim periods within those years, beginning after December 15, 2019. We plan to adopt this standard on January 1, 2020 and are currently evaluating the impact of this new standard on our consolidated financial statements.

In August 2018, the FASB issued ASU No. 2018-15, “Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract,” which requires a customer that is a party to a cloud computing service contract to follow the internal-use software guidance in ASC 350-40 to determine which implementation costs to defer and recognize as an asset. This standard is effective for fiscal years, and interim periods within those years, beginning after December 15, 2019. We plan to adopt this standard on January 1, 2020 and are currently evaluating the impact of this new standard on our consolidated financial statements.

Composition of Certain Balance Sheet Items

9 Months Ended

Sep. 30, 2018

Balance Sheet Related Disclosures [Abstract]

Composition of Certain Balance Sheet Items

2. Composition of Certain Balance Sheet Items

Inventory

The composition of inventory was as follows:

	September 30,			December 31,
	2018			2017
	(in thousands)
Raw materials	$	1,300		$	4,287
Work in progress		3,959			64
Finished goods		7,463			4,025
Total inventory		12,722			8,376
Less strategic inventory classified as non-current		(7,360	)		(3,800	)
Total inventory classified as current	$	5,362		$	4,576

In order to be prepared for potential demand for Korlym and because we rely on single-source manufacturers of both the active pharmaceutical ingredient (“API”) for Korlym and Korlym tablets, we have purchased significant inventory quantities of these materials. We classify inventory we do not expect to sell within 12 months of the balance sheet date as “Strategic Inventory,” a long-term asset.

Other Accrued Liabilities

Other accrued liabilities consisted of the following:

	September 30,		December 31,
	2018		2017
	(in thousands)
Government rebates	$	11,158	$	7,961
Accrued compensation		6,407		8,574
Income taxes payable		1,583		66
Legal fees		516		276
Professional fees		333		207
Accrued selling and marketing costs		611		208
Accrued manufacturing costs		20		955
Other		264		496
Total other accrued liabilities	$	20,892	$	18,743

Available-for-Sale Securities and Fair Value Measurements

9 Months Ended

Sep. 30, 2018

Available For Sale Securities And Fair Value Measurements [Abstract]

Available-for-Sale Securities and Fair Value Measurements

3. Available-for-Sale Securities and Fair Value Measurements

Our available-for-sale securities included:

	Fair Value	Estimated Fair Value
	Hierarchy	September 30,		December 31,
	Level	2018		2017
		(in thousands)
Corporate bonds	Level 2	$	40,264	$	26,116
Commercial paper	Level 2		73,355		32,637
Asset-backed securities	Level 2		10,946		—
Repurchase agreements	Level 2		20,000		—
U.S. treasury securities	Level 1		38,216		14,210
Money market funds	Level 1		1,474		14,979
Total Marketable securities		$	184,255	$	87,942

Classified as:
Cash equivalents		$	21,474	$	14,979
Short-term marketable securities			161,300		57,682
Long-term marketable securities			1,481		15,281
Total marketable securities		$	184,255	$	87,942

The estimated fair value of marketable securities is based on quoted market prices for these or similar investments obtained from a commercial pricing service. The fair value of marketable securities classified within Level 2 is based upon inputs that may include benchmark yields, reported trades, broker/dealer quotes and issuer spreads. Our accumulated other comprehensive loss on our balance sheets consisted of net unrealized losses on available-for-sale investments of $0.1 million at September 30, 2018 and $0.1 million at December 31, 2017, net of tax impact of $25,000 and $0, respectively.

As of September 30, 2018, all our marketable securities had original maturities of less than two years. The weighted-average maturity of our holdings was four months. None of our marketable securities changed from one fair value hierarchy to another during the three and nine months ended September 30, 2018.

Debt Obligation	9 Months Ended
Debt Obligation	Sep. 30, 2018
Debt Disclosure [Abstract]
Debt Obligation	4. Debt Obligation As discussed in Note 1, Basis of Presentation and Summary of Significant Accounting Policies, Debt Obligation, under the Financing Agreement with Biopharma we made quarterly payments to Biopharma equal to 20 percent of Korlym sales in that quarter. To secure our obligation, we granted Biopharma a security interest in our patents, trademarks, trade names, domain names, copyrights, know-how, books, records and regulatory approvals related to Korlym and certain other assets and any proceeds from them. Biopharma’s right to receive payments expired once our payments reached a total of $45.0 million, which occurred in July 2017. Our obligations under the Financing Agreement and Biopharma’s security interests in our assets are now extinguished. We recorded no interest expense for the three and nine months ended September 30, 2018, compared to $37,000 and $0.5 million for the three and nine months ended September 30, 2017, respectively. Total accreted interest for the full term of the Financing Agreement was $15.0 million. We capitalized $0.1 million of issuance costs related to the Financing Agreement, which we amortized over the term of the obligation. At September 30, 2018 and December 31, 2017, there were no unamortized issuance costs.

Commitments and Contingencies

9 Months Ended

Sep. 30, 2018

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

5. Commitments and Contingencies

Leases

In February 2016, we extended the lease for our office space through 2019 and added more space. In May 2016, we terminated our lease early and replaced it with a new one effective through March 31, 2019. In March 2018, we amended that lease to add more space. Rent expense for each of the three months ended September 30, 2018 and 2017 was $0.3 million. Rent expense for the nine months ended September 30, 2018 and 2017 was $0.9 million and $0.8 million, respectively.

As of September 30, 2018, future minimum lease payments under non-cancelable operating leases were as follows:

	Lease
	Payments
2018 (remainder)	$	346
2019		342
Thereafter		—
Total	$	688

Contingencies

In the ordinary course of business, we may be subject to legal claims and regulatory actions that could have a material adverse effect on our business or financial position. We assess our potential liability in such situations by analyzing potential outcomes, assuming various litigation, regulatory and settlement strategies. If we determine a loss is probable and its amount can be reasonably estimated, we accrue an amount equal to the estimated loss.

No losses and no provision for a loss contingency have been recorded to date.

Stockholder’s Equity

9 Months Ended

Sep. 30, 2018

Equity [Abstract]

Stockholder’s Equity

6. Stockholder’s Equity

Stock Option Plans

We have two stock option plans – the 2004 Equity Incentive Plan (the “2004 Plan”) and the 2012 Incentive Award Plan (the “2012 Plan”). In February 2018, our Board of Directors authorized a 4.6 million increase in the shares available for grant under the 2012 Plan pursuant to the annual increase provisions of the 2012 Plan.

During the nine months ended September 30, 2018, we issued 1,408,000 shares of our common stock upon the exercise of stock options.

The following table summarizes our stock-based compensation:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2018		2017		2018		2017
	(in thousands)				(in thousands)
Research and development	$	1,961	$	1,049	$	5,388	$	2,552
Selling, general and administrative		4,549		2,574		12,093		6,977
Total stock-based compensation	$	6,510	$	3,623	$	17,481	$	9,529

Stock Repurchase Program

On August 9, 2018, we announced that our Board of Directors had approved a program to repurchase up to $100 million of our common stock (the “Stock Repurchase Program”). Unless it is terminated or suspended prior to its expiration, the Stock Repurchase Program will remain in effect until June 30, 2019. The timing and amount of any repurchases pursuant to the Stock Repurchase Program will be determined based on market conditions, our stock price and other factors. The Stock Repurchase Program does not require us to acquire any specific number of shares and it may be modified, suspended or discontinued at any time without notice. Repurchases pursuant to the Stock Repurchase Program may be made through a variety of methods, including open market purchases, privately negotiated transactions, block trades, accelerated share repurchase transactions or any combination of such methods.

During the three months ended September 30, 2018, we repurchased 674,000 shares of common stock under the Stock Repurchase Program in open market transactions at an average price of $13.21 per share, for an aggregate purchase price of $8.9 million. Shares repurchased are recorded as treasury stock at cost on our consolidated balance sheet. At September 30, 2018, $91.1 million of the current authorization remained available for the repurchase of shares of our common stock.

Net Income Per Share

9 Months Ended

Sep. 30, 2018

Earnings Per Share [Abstract]

Net Income Per Share

7. Net Income Per Share

We compute basic and diluted net income per share by dividing our net income by the weighted-average number of common shares outstanding during the period. We used the treasury stock method to determine the number of dilutive shares of common stock resulting from the potential exercise of stock options. The statements of comprehensive income show the computation of net income per share for each period, including the number of weighted-average shares outstanding.

The following table shows the computation of net income per share for each period:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2018		2017		2018		2017
	(in thousands)				(in thousands)
Numerator:
Net income	$	17,747	$	13,757	$	53,402	$	30,792
Denominator:
Weighted-average shares used to compute basic net income per share		115,798		113,603		115,394		113,242
Dilutive effect of employee stock options		10,361		12,048		11,773		10,175
Weighted-average shares used to compute diluted net income per share		126,159		125,651		127,167		123,417
Net income per share
Basic	$	0.15	$	0.12	$	0.46	$	0.27
Diluted	$	0.14	$	0.11	$	0.42	$	0.25

On a weighted-average basis, 5.9 million and 4.7 million stock options outstanding during the three and nine months ended September 30, 2018, respectively, compared to 1.1 million and 3.3 million stock options outstanding during the three and nine months ended September 30, 2017, respectively, were excluded from the computation of diluted net income per share because including them would have reduced dilution.

The following table presents information on securities outstanding as of the end of each period that could potentially dilute the per share data:

	September 30,
	2018		2017
	(in thousands)
Stock options outstanding		23,315		20,729

Income Taxes	9 Months Ended
Income Taxes	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	8. Income taxes We recorded an income tax expense of $6.0 million and $12.8 million for the three and nine months ended September 30, 2018, respectively, compared to a benefit of $0.1 million and an expense of $0.1 million for the three and nine months ended September 30, 2017, respectively. Income tax expense for the three and nine months ended September 30, 2018 was primarily due to the reduction of deferred tax assets of $5.0 million and $10.6 million, respectively, caused by our utilization of federal and state net operating losses and income tax expense of $1.0 million and $2.2 million, respectively, incurred in states where we have no net operating loss carryforwards to offset our tax obligations. Income tax expense for the three and nine months ended September 30, 2017 reflects income tax incurred in states where we have no net operating loss carryforwards to offset our tax obligations. Our effective tax rate differed from the federal statutory rate due to state income taxes and non-deductible stock-based compensation, which increased our tax expense, offset by research and development tax credits and the reduction in taxable income arising from the exercise of employee stock options during the reporting period. Each quarter, we assess our ability to use our deferred tax assets to offset our expected federal and state taxable income. In the fourth quarter of 2017, we determined that it was more likely than not that we would generate sufficient taxable income to utilize our federal and state deferred tax assets in every state except California. We therefore included in our balance sheet the net value of all our deferred tax assets except those applicable to California. All tax years from Corcept’s inception remain open to examination by the Internal Revenue Service, the California Franchise Tax Board and other state taxing authorities. The Tax Cuts and Jobs Act of 2017 (“Tax Act”), which became law on December 22, 2017, significantly changed federal income tax law. Among other things, effective January 1, 2018, the new law reduced the corporate income tax rate from 35 percent to 21 percent, repealed the corporate alternative minimum tax, limited some business deductions, modified the maximum deduction of future net operating losses generated with no carryback but an indefinite carryforward provision and extended the compensation deduction limit applicable to certain highly-compensated executives of publicly traded companies to cover additional executive roles. Accounting Standards Codification (ASC) 740, Income Taxes, requires companies to recognize the effect of tax law changes, such as those enacted by the Tax Act, in the period such changes take effect. We have adjusted our deferred taxes based on the reduction of the U.S. federal corporate tax rate from 35 percent to 21 percent and assessed the realizability of our deferred tax assets based on our current understanding of the new law. At September 30, 2018, the accounting for the impacts of the Tax Act was substantially complete and we do not expect material changes to the amounts recorded. We will continue to assess the Tax Act’s impact for the rest of 2018, including its interpretation by regulatory authorities, and will adjust our disclosures and financial presentation as necessary.

Basis of Presentation and Summary of Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2018

Accounting Policies [Abstract]

Basis of Presentation

Principles of Consolidation

Use of Estimates

Fair Value Measurements

Cash and Cash Equivalents and Marketable Securities

Concentration of Credit Risk

Inventory and Cost of Sales

We classify inventory we do not expect to sell or use in clinical studies within 12 months of the balance sheet date as strategic inventory, a noncurrent asset.

Debt Obligation

Revenue

Confirmation of coverage by private or government insurance or by a third-party charity is a prerequisite for selling Korlym to a patient.

The following table summarizes activity in each of the product revenue allowance and reserve categories for the nine months ended September 30, 2018.

	Chargebacks			Government Rebates			Total
	(in thousands)
Balance at December 31, 2017:	$	927		$	7,961		$	8,888
Provision related to current period sales		2,539			21,668			24,207
Provision related to prior period sales		—			181			181
Credit or payments made during the period		(2,163	)		(18,653	)		(20,816	)
Balance at September 30, 2018:	$	1,303		$	11,157		$	12,460

Research and Development

Segment Reporting

Stock-Based Compensation

We recognize the expense of options granted to non-employees based on their fair value at the time of vesting.

Recently Adopted Accounting Pronouncements

Recently Issued Accounting Pronouncements Not Yet Adopted

Income Taxes

Accounting Standards Codification (ASC) 740, Income Taxes, requires companies to recognize the effect of tax law changes, such as those enacted by the Tax Act, in the period such changes take effect. We have adjusted our deferred taxes based on the reduction of the U.S. federal corporate tax rate from 35 percent to 21 percent and assessed the realizability of our deferred tax assets based on our current understanding of the new law. At September 30, 2018, the accounting for the impacts of the Tax Act was substantially complete and we do not expect material changes to the amounts recorded. We will continue to assess the Tax Act’s impact for the rest of 2018, including its interpretation by regulatory authorities, and will adjust our disclosures and financial presentation as necessary.

Basis of Presentation and Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2018

Accounting Policies [Abstract]

Schedule of Product Revenue Allowance and Reserve Categories

The following table summarizes activity in each of the product revenue allowance and reserve categories for the nine months ended September 30, 2018.

	Chargebacks			Government Rebates			Total
	(in thousands)
Balance at December 31, 2017:	$	927		$	7,961		$	8,888
Provision related to current period sales		2,539			21,668			24,207
Provision related to prior period sales		—			181			181
Credit or payments made during the period		(2,163	)		(18,653	)		(20,816	)
Balance at September 30, 2018:	$	1,303		$	11,157		$	12,460

Composition of Certain Balance Sheet Items (Tables)

9 Months Ended

Sep. 30, 2018

Balance Sheet Related Disclosures [Abstract]

Composition of Inventory

	September 30,			December 31,
	2018			2017
	(in thousands)
Raw materials	$	1,300		$	4,287
Work in progress		3,959			64
Finished goods		7,463			4,025
Total inventory		12,722			8,376
Less strategic inventory classified as non-current		(7,360	)		(3,800	)
Total inventory classified as current	$	5,362		$	4,576

Other Accrued Liabilities

	September 30,		December 31,
	2018		2017
	(in thousands)
Government rebates	$	11,158	$	7,961
Accrued compensation		6,407		8,574
Income taxes payable		1,583		66
Legal fees		516		276
Professional fees		333		207
Accrued selling and marketing costs		611		208
Accrued manufacturing costs		20		955
Other		264		496
Total other accrued liabilities	$	20,892	$	18,743

Available-for-Sale Securities and Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2018

Available For Sale Securities And Fair Value Measurements [Abstract]

Schedule of Available-for-Sale Securities

Our available-for-sale securities included:

	Fair Value	Estimated Fair Value
	Hierarchy	September 30,		December 31,
	Level	2018		2017
		(in thousands)
Corporate bonds	Level 2	$	40,264	$	26,116
Commercial paper	Level 2		73,355		32,637
Asset-backed securities	Level 2		10,946		—
Repurchase agreements	Level 2		20,000		—
U.S. treasury securities	Level 1		38,216		14,210
Money market funds	Level 1		1,474		14,979
Total Marketable securities		$	184,255	$	87,942

Classified as:
Cash equivalents		$	21,474	$	14,979
Short-term marketable securities			161,300		57,682
Long-term marketable securities			1,481		15,281
Total marketable securities		$	184,255	$	87,942

Commitments and Contingencies (Tables)

9 Months Ended

Sep. 30, 2018

Commitments And Contingencies Disclosure [Abstract]

Schedule of Future Minimum Lease Payments under Non-Cancelable Operating Leases

As of September 30, 2018, future minimum lease payments under non-cancelable operating leases were as follows:

	Lease
	Payments
2018 (remainder)	$	346
2019		342
Thereafter		—
Total	$	688

Stockholder’s Equity (Tables)

9 Months Ended

Sep. 30, 2018

Equity [Abstract]

Summary of Stock-Based Compensation

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2018		2017		2018		2017
	(in thousands)				(in thousands)
Research and development	$	1,961	$	1,049	$	5,388	$	2,552
Selling, general and administrative		4,549		2,574		12,093		6,977
Total stock-based compensation	$	6,510	$	3,623	$	17,481	$	9,529

Net Income Per Share (Tables)

9 Months Ended

Sep. 30, 2018

Earnings Per Share [Abstract]

Schedule of Computation of Net Income Per Share

The following table shows the computation of net income per share for each period:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2018		2017		2018		2017
	(in thousands)				(in thousands)
Numerator:
Net income	$	17,747	$	13,757	$	53,402	$	30,792
Denominator:
Weighted-average shares used to compute basic net income per share		115,798		113,603		115,394		113,242
Dilutive effect of employee stock options		10,361		12,048		11,773		10,175
Weighted-average shares used to compute diluted net income per share		126,159		125,651		127,167		123,417
Net income per share
Basic	$	0.15	$	0.12	$	0.46	$	0.27
Diluted	$	0.14	$	0.11	$	0.42	$	0.25

Securities Outstanding that could Potentially Dilute Per Share Data

The following table presents information on securities outstanding as of the end of each period that could potentially dilute the per share data:

	September 30,
	2018		2017
	(in thousands)
Stock options outstanding		23,315		20,729

Basis of Presentation and Summary of Significant Accounting Policies (Narrative) (Details)	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018 Segment Group
Accounting Policies [Line Items]
Date of incorporation		May 01, 1998
Entity incorporated, State		Delaware
Number of operating segments \| Segment		1
Number of customer groups \| Group		2
Financing Agreement with Biopharma
Accounting Policies [Line Items]
Payments as equivalent percentage of sales		20.00%
Debt obligation, periodic payment		quarterly
Maximum
Accounting Policies [Line Items]
Investments maturity at time of purchase		36 months
Maximum \| Sales Revenue, Net \| Customer Concentration Risk
Accounting Policies [Line Items]
Percentage of sales to one specialty distributor	1.00%	1.00%

Basis of Presentation and Summary of Significant Accounting Policies (Summary of Product Revenue Allowance and Reserve Categories) (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018 USD ($)
Accounts Notes And Loans Receivable [Line Items]
Balance at December 31, 2017:	$ 8,888
Provision related to current period sales	24,207
Provision related to prior period sales	181
Credit or payments made during the period	(20,816)
Balance at September 30, 2018:	12,460
Chargebacks
Accounts Notes And Loans Receivable [Line Items]
Balance at December 31, 2017:	927
Provision related to current period sales	2,539
Provision related to prior period sales	0
Credit or payments made during the period	(2,163)
Balance at September 30, 2018:	1,303
Government Rebates
Accounts Notes And Loans Receivable [Line Items]
Balance at December 31, 2017:	7,961
Provision related to current period sales	21,668
Provision related to prior period sales	181
Credit or payments made during the period	(18,653)
Balance at September 30, 2018:	$ 11,157

Composition of Certain Balance Sheet Items (Composition of Inventory) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Balance Sheet Related Disclosures [Abstract]
Raw materials	$ 1,300	$ 4,287
Work in progress	3,959	64
Finished goods	7,463	4,025
Total inventory	12,722	8,376
Less strategic inventory classified as non-current	(7,360)	(3,800)
Total inventory classified as current	$ 5,362	$ 4,576

Composition of Certain Balance Sheet Items (Other Accrued Liabilities) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Balance Sheet Related Disclosures [Abstract]
Government rebates	$ 11,158	$ 7,961
Accrued compensation	6,407	8,574
Income taxes payable	1,583	66
Legal fees	516	276
Professional fees	333	207
Accrued selling and marketing costs	611	208
Accrued manufacturing costs	20	955
Other	264	496
Total other accrued liabilities	$ 20,892	$ 18,743

Available-for-Sale Securities and Fair Value Measurements (Schedule of Available-for-Sale Securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Schedule Of Available For Sale Securities [Line Items]
Short-term marketable securities	$ 161,300	$ 57,682
Long-term marketable securities	1,481	15,281
Estimated Fair Value
Schedule Of Available For Sale Securities [Line Items]
Marketable securities	184,255	87,942
Cash equivalents	21,474	14,979
Short-term marketable securities	161,300	57,682
Long-term marketable securities	1,481	15,281
Corporate Bonds \| Estimated Fair Value \| Level 2
Schedule Of Available For Sale Securities [Line Items]
Marketable securities	40,264	26,116
Commercial Paper \| Estimated Fair Value \| Level 2
Schedule Of Available For Sale Securities [Line Items]
Marketable securities	73,355	32,637
Asset Backed Securities \| Estimated Fair Value \| Level 2
Schedule Of Available For Sale Securities [Line Items]
Marketable securities	10,946	0
Repurchase Agreements \| Estimated Fair Value \| Level 2
Schedule Of Available For Sale Securities [Line Items]
Marketable securities	20,000	0
U.S. Treasury Securities \| Estimated Fair Value \| Level 1
Schedule Of Available For Sale Securities [Line Items]
Marketable securities	38,216	14,210
Money Market Funds \| Estimated Fair Value \| Level 1
Schedule Of Available For Sale Securities [Line Items]
Marketable securities	$ 1,474	$ 14,979

Available-for-Sale Securities and Fair Value Measurements (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Available For Sale Securities And Fair Value Measurements [Abstract]
Net unrealized losses on available-for-sale investments	$ 50,000	$ 3,000	$ (77,000)	$ (14,000)	$ (100,000)
Net unrealized losses on available-for-sale investments, tax impact	(16,000)	$ 0	$ 25,000	$ 0	$ 0
Maximum maturity period			2 years
Weighted average maturity period			4 months
Fair value, assets, Level 1 to Level 2 transfers, amount	0		$ 0
Fair value, assets, Level 2 to Level 1 transfers, amount	$ 0		$ 0

Debt Obligation (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended
Debt Obligation (Narrative) (Details) - USD ($)	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Contractual Obligation [Line Items]
Accretion of interest expense	$ 0	$ 37,000	$ 0	$ 500,000
Issuance costs capitalized	100,000		100,000
Unamortized issuance cost	0		$ 0		$ 0
Financing Agreement with Biopharma
Contractual Obligation [Line Items]
Payments as equivalent percentage of sales			20.00%
Debt obligation, periodic payment			quarterly
Cumulative payments to be made under financing agreement	$ 45,000,000		$ 45,000,000
Accretion of interest expense			$ 15,000,000

Commitments and Contingencies (Narratives) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Commitments And Contingencies Disclosure [Abstract]
Lease expiration date			Mar. 31, 2019
Rent expenses	$ 300,000	$ 300,000	$ 900,000	$ 800,000
Losses for contingent liability	$ 0		0
Provision for a loss contingency			$ 0

Commitments and Contingencies (Schedule of Future Minimum Lease Payments under Non-Cancelable Operating Leases) (Details) $ in Thousands	Sep. 30, 2018 USD ($)
Operating Leases Future Minimum Payments Due [Abstract]
2018 (remainder)	$ 346
2019	342
Thereafter	0
Total	$ 688

Stockholder's Equity (Narrative) (Details)		1 Months Ended	3 Months Ended	9 Months Ended
Stockholder's Equity (Narrative) (Details)	Aug. 09, 2018 USD ($)	Feb. 28, 2018 shares	Sep. 30, 2018 USD ($) $ / shares shares	Sep. 30, 2018 USD ($) item shares
Shareholders Equity [Line Items]
Number of stock option plans \| item				2
Common shares issued upon exercise of options \| shares				1,408,000
Stock Repurchase Program \| Common Stock
Shareholders Equity [Line Items]
Stock repurchase amount \| $	$ 100,000,000
Stock repurchase program expiration date	Jun. 30, 2019
Common stock repurchased, shares \| shares			674,000
Common stock repurchased, average price per share \| $ / shares			$ 13.21
Common stock repurchased, value \| $			$ 8,900,000
Stock repurchase program, remaining authorized amount available for repurchase \| $			$ 91,100,000	$ 91,100,000
2012 Equity Incentive Award Plan
Shareholders Equity [Line Items]
Increase in shares authorized for grant \| shares		4,600,000

Stockholder's Equity (Summary of Stock-Based Compensation) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 6,510	$ 3,623	$ 17,481	$ 9,529
Research And Development Expense
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	1,961	1,049	5,388	2,552
Selling, General And Administrative Expense
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 4,549	$ 2,574	$ 12,093	$ 6,977

Schedule of Computation of Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Numerator:
Net income	$ 17,747	$ 13,757	$ 53,402	$ 30,792
Denominator:
Weighted-average shares used to compute basic net income per share	115,798	113,603	115,394	113,242
Dilutive effect of employee stock options	10,361	12,048	11,773	10,175
Weighted-average shares used to compute diluted net income per share	126,159	125,651	127,167	123,417
Net income per share
Basic	$ 0.15	$ 0.12	$ 0.46	$ 0.27
Diluted	$ 0.14	$ 0.11	$ 0.42	$ 0.25

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(19))
-URI http://asc.fasb.org/extlink&oid=114873790&loc=SL114874131-224263

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=109260490&loc=d3e1337-109256

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 55
-Paragraph 52
-URI http://asc.fasb.org/extlink&oid=109256448&loc=d3e4984-109258

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(21))
-URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109260490&loc=d3e1252-109256

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(23))
-URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 60B
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=109260490&loc=SL5780133-109256

+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 55
-Paragraph 52
-URI http://asc.fasb.org/extlink&oid=109256448&loc=d3e4984-109258

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109260490&loc=d3e1252-109256

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(23))
-URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=109260490&loc=d3e1337-109256

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(21))
-URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 60B
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=109260490&loc=SL5780133-109256

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(19))
-URI http://asc.fasb.org/extlink&oid=114873790&loc=SL114874131-224263

+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Net Income Per Share (Details) - shares shares in Millions	3 Months Ended		9 Months Ended
Net Income Per Share (Details) - shares shares in Millions	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Stock Options to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average options excluded from the computation of diluted net income per share	5.9	1.1	4.7	3.3

Net Income Per Share (Securities Outstanding that could Potentially Dilute Per Share Data) (Details) - shares shares in Thousands	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
Securities outstanding that could potentially dilute per share data	23,315	20,729

Income Taxes - (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
Income Taxes - (Narrative) (Details) - USD ($)	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income tax expense (benefit)	$ 5,981,000	$ (48,000)	$ 12,811,000	$ 129,000
Reduction of deferred tax assets	5,000,000		10,600,000
State income tax expense	1,000,000		2,200,000
Net operating loss carryforwards	$ 0	$ 0	$ 0	$ 0
Corporate income tax rate			21.00%		35.00%