Stockholders' Equity	12 Months Ended
Stockholders' Equity	Dec. 31, 2020
Stockholders' Equity Note [Abstract]
Stockholders' Equity	Stockholders’ Equity On January 21, 2015, the Company’s Board approved a share repurchase program authorizing the repurchase of up to an aggregate of 20.0 million shares (the “2015 Repurchase Program”). Share repurchases under the 2015 Repurchase Program were made through the open market, established plans or privately negotiated transactions in accordance with all applicable securities laws, rules, and regulations. During the years ended December 31, 2020 and 2019, the Company did not repurchase any shares of its common stock under the 2015 Repurchase Program. On October 29, 2020, the Company’s Board approved a new share repurchase program authorizing the repurchase of up to an aggregate of 20.0 million shares (the “2020 Repurchase Program”). Share repurchases under the 2020 Repurchase Program may be made through the open market, established plans or privately negotiated transactions in accordance with all applicable securities laws, rules, and regulations. There is no expiration date applicable to the 2020 Repurchase Program. The 2020 Repurchase Program replaced the previous program approved by the Board in January 2015 and canceled the remaining shares outstanding as part of the previous authorization. On November 11, 2020, the Company entered into an accelerated share repurchase program with Deutsche Bank AG, London Branch as counterparty, through its agent Deutsche Bank Securities Inc. (“Deutsche Bank”) (the “2020 ASR Program”). The 2020 ASR Program was part of the broader share repurchase program previously authorized by the Company’s Board on October 29, 2020. Under the 2020 ASR Program, the Company pre-paid to Deutsche Bank the $50.0 million purchase price for its common stock and, in turn, the Company received an initial delivery of approximately 2.6 million shares of its common stock from Deutsche Bank in the fourth quarter of 2020, which were retired and recorded as a $40.0 million reduction to stockholders’ equity. The remaining $10.0 million of the initial payment was recorded as a reduction to stockholders’ equity as an unsettled forward contract indexed to the Company’s stock. The number of shares to be ultimately purchased by the Company will be determined based on the volume-weighted-average price of the common stock during the terms of the transaction, minus an agreed upon discount between the parties. The 2020 ASR Program is expected to be completed within six months from the beginning of the program. There were no other repurchases of the Company’s common stock during 2020. As of December 31, 2020, there remained an outstanding authorization to repurchase approximately 17.4 million shares of the Company’s outstanding common stock under the current share repurchase program. The Company records share repurchases as a reduction to stockholders’ equity. The Company records a portion of the purchase price of the repurchased shares as an increase to accumulated deficit when the price of the shares repurchased exceeds the average original proceeds per share received from the issuance of common stock. During the year ended December 31, 2020, the cumulative price of $31.5 million was recorded as an increase to accumulated deficit. Convertible Note Hedge Transactions On November 14, 2017 and November 16, 2017, in connection with the 2023 Notes, the Company entered into the Convertible Note Hedge Transactions with respect to the Common Stock, with the Counterparties. The Company paid an aggregate amount of approximately $33.5 million to the Counterparties for the Convertible Note Hedge Transactions. The Convertible Note Hedge Transactions cover, subject to anti-dilution adjustments substantially similar to those in the 2023 Notes, approximately 9.1 million shares of Common Stock, the same number of shares underlying the 2023 Notes, at a strike price that corresponds to the initial conversion price of the 2023 Notes, and are exercisable upon conversion of the 2023 Notes. The Convertible Note Hedge Transactions will expire upon the maturity of the 2023 Notes. The Convertible Note Hedge Transactions are expected generally to reduce the potential dilution to the Common Stock upon conversion of the 2023 Notes and/or offset any cash payments the Company is required to make in excess of the principal amount of the converted 2023 Notes, as the case may be, in the event that the market price per share of the Common Stock, as measured under the terms of the Convertible Note Hedge Transactions, is greater than the strike price of the Convertible Note Hedge Transactions. The Convertible Note Hedge Transactions are separate transactions, entered into by the Company with the Counterparties, and are not part of the terms of the 2023 Notes. Holders of the 2023 Notes will not have any rights with respect to the Convertible Note Hedge Transactions. Refer to Note 12, “Convertible Notes,” for additional details. Warrant Transactions On November 14, 2017 and November 16, 2017, in connection with the 2023 Notes, the Company sold the Warrants to the Counterparties to acquire, collectively, subject to anti-dilution adjustments, approximately 9.1 million shares of the Common Stock at an initial strike price of approximately $23.30 per share, which represents a premium of 60% over the last reported sale price of the Common Stock of $14.56 on November 14, 2017. The Company received aggregate proceeds of approximately $23.2 million from the sale of the Warrants to the Counterparties. The Warrants were sold in private placements to the Counterparties pursuant to an exemption from the registration requirements of the Securities Act afforded by Section 4(a)(2) of the Securities Act. If the market price per share of the Common Stock, as measured under the terms of the Warrants, exceeds the strike price of the Warrants, the Warrants could have a dilutive effect, unless the Company elects, subject to certain conditions, to settle the Warrants in cash. The Warrants are separate transactions, entered into by the Company with the Counterparties, and are not part of the terms of the 2023 Notes. Holders of the 2023 Notes will not have any rights with respect to the Warrants. Refer to Note 12, “Convertible Notes,” for additional details.