Basic and Diluted Net Income (Loss) per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended
	Aug. 17, 2015	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Components of basic and diluted net income (loss) per share
Net income (loss)		$ (7,527)	$ 12,904
Weighted average common shares outstanding		34,739	27,213
Effect of dilutive securities:
Stock options and RSUs (in shares)			1,552
Warrants (in shares)			7,382
Convertible 2.5% notes (in shares)			2,098
Shares used in calculating dilutive net income (loss) per share (in shares)		34,739	38,245
Net income (loss) per share:
Basic (in dollars per share)		$ (0.22)	$ 0.47
Diluted (in dollars per share)		$ (0.22)	$ 0.39
Anti-dilutive securities (in shares)		18,123	1,154
Employee and Non Employee Stock Option
Net income (loss) per share:
Anti-dilutive securities (in shares)		2,455	856
Employee and Non Employee Restricted Stock Units
Net income (loss) per share:
Anti-dilutive securities (in shares)		904	298
Warrants
Net income (loss) per share:
Anti-dilutive securities (in shares)		7,382
Convertible 2.5% notes
Net income (loss) per share:
Anti-dilutive securities (in shares)		7,382
2.5 Percent Convertible Notes
Basic and Diluted Net Income (Loss) per Share
Principal amount of debt at time of issuance		$ 200,000
Interest rate (as a percent)		2.50%		2.50%
2015 Term Loan Facility
Basic and Diluted Net Income (Loss) per Share
Debt term	6 years	6 years
Principal amount of debt at time of issuance	$ 350,000	$ 350,000