Basic and Diluted Net Income (Loss) per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
	Aug. 17, 2015	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Components of basic and diluted net income (loss) per share
Net income (loss)		$ (596)	$ 33,258	$ (8,123)	$ 46,162
Weighted average common shares outstanding		34,223	30,636	34,481	28,934
Effect of dilutive securities:
Stock options and RSUs (in shares)			1,785		1,639
Warrants (in shares)			3,378		2,836
Convertible 2.5% notes (in shares)			7,382		7,382
Shares used in calculating dilutive net income (loss) per share (in shares)		34,223	43,181	34,481	40,791
Net income (loss) per share:
Basic (in dollars per share)		$ (0.02)	$ 1.09	$ (0.24)	$ 1.60
Diluted (in dollars per share)		$ (0.02)	$ 0.82	$ (0.24)	$ 1.23
Anti-dilutive securities (in shares)		17,769	669	18,432	1,050
Employee and Non Employee Stock Option
Net income (loss) per share:
Anti-dilutive securities (in shares)		2,525	601	2,694	709
Employee and Non Employee Restricted Stock Units
Net income (loss) per share:
Anti-dilutive securities (in shares)		480	68	974	341
Warrants
Net income (loss) per share:
Anti-dilutive securities (in shares)		7,382		7,382
Convertible 2.5% notes
Net income (loss) per share:
Anti-dilutive securities (in shares)		7,382		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		$ 200,000
Interest rate (as a percent)		2.50%		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		$ 350,000