Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands		Total	Common Stock [Member]		Additional Paid-In Capital [Member]	[1]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings (Accumulated Deficit) [Member]
Balances at Dec. 31, 2012		$ 73,645	$ 1,495	[1]	$ 363,665		$ 33	$ (291,548)
Balance, Shares at Dec. 31, 2012	[1]		149,549,878
Common stock value issued under equity incentive and employee stock purchase plans		8,870	$ 20	[1]	8,850
Common stock shares issued under equity incentive and employee stock purchase plans	[1]		2,005,218
Common stock issued for warrant exercises, net of shares withheld for exercise price		0	$ 1	[1]	(1)		0	0
Common stock issued for warrant exercises, net of shares withheld for exercise price, Shares	[1]		50,944
Stock-based compensation expense		37,078			37,078
Change in comprehensive income		(33)					$ (33)
Net income (loss)		(42,613)						(42,613)
Balances at Dec. 31, 2013		76,947	$ 1,516	[1]	409,592			(334,161)
Balance, Shares at Dec. 31, 2013	[1]		151,606,040
Common stock value issued under equity incentive and employee stock purchase plans		33,882	$ 46	[1]	33,836
Common stock shares issued under equity incentive and employee stock purchase plans	[1]		4,628,414
Stock-based compensation expense		45,134			45,134
Excess tax benefits from stock-based compensation		16,965			16,965
Tax shortfalls from stock-based compensation		(77)			(77)
Repayment of Convertible Notes		(4)			(4)
Net income (loss)		276,452						276,452
Balances at Dec. 31, 2014		$ 449,299	$ 1,562	[1]	505,446			(57,709)
Balance, Shares at Dec. 31, 2014		156,234,454	156,234,454	[1]
Common stock value issued under equity incentive and employee stock purchase plans		$ 21,459	$ 21	[1]	21,438
Common stock shares issued under equity incentive and employee stock purchase plans	[1]		2,032,312
Stock-based compensation expense		54,862			54,862
Excess tax benefits from stock-based compensation		100,243			100,243
Tax shortfalls from stock-based compensation		(259)			(259)
Common stock issued for conversion of Convertible Notes, Amount		(11,183)	$ 56	[1]	(11,239)
Common stock issued for conversion of Convertible Notes, Shares	[1]		5,638,576
Tax impact of extinguishment of Convertible Notes		11,847			11,847
Reclassification of accrued interest on Convertible Notes upon conversion		1,686			1,686
Stock dividend					817			(817)
Change in comprehensive income		(10)
Net income (loss)		244,725						244,725
Balances at Dec. 31, 2015		$ 872,679	$ 1,639	[1]	$ 684,841			$ 186,199
Balance, Shares at Dec. 31, 2015		163,905,342	0	[1]

[1] All share, par, and additional paid-in capital amounts have been retroactively adjusted to reflect the Company’s September 15, 2015, two-for-one forward stock split effected through a stock dividend. This stock split resulted in the issuance of approximately 81.7 million shares of the Company’s common stock.