CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Company Common Stock Held By Nonqualified Deferred Compensation Plan	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning Balance at Dec. 31, 2012	$ 1,015,763	$ 126	$ 1,561,890	$ (6,603)	$ (202)	$ (539,448)
Beginning Balance (in shares) at Dec. 31, 2012		125,809,000
Net loss	(176,353)					(176,353)
Other comprehensive income (loss)	5,220				5,220
Purchase of capped call share options, net of tax	(19,065)		(19,065)
Issuance of convertible debt, net of tax and offering costs	99,879		99,879
Issuance of common stock under the 2006 Employee Stock Purchase Plan (the ESPP) (in shares)		254,000
Issuance of common stock under the 2006 Employee Stock Purchase Plan (the ESPP)	6,839		6,839
Exercise of common stock options (in shares)		2,885,000
Exercise of common stock options	65,740	$ 4	65,736
Excess tax benefit from stock option exercises	733		733
Conversion of convertible notes, net (in shares)		14,313,000
Conversion of convertible notes, net	283,319	$ 14	283,305
Restricted stock vested during the period, net (in shares)		203,000
Restricted stock vested during the period, net	(6,397)		(6,397)
Common stock held by Nonqualified Deferred Compensation Plan	(818)			(818)
Stock-based compensation	66,181		66,181
Ending Balance at Dec. 31, 2013	1,341,041	$ 144	2,059,101	(7,421)	5,018	(715,801)
Ending Balance (in shares) at Dec. 31, 2013		143,464,000
Net loss	(133,969)					(133,969)
Other comprehensive income (loss)	22,448				22,448
Issuance of common stock, net of offering costs (in shares)		1,500,000
Issuance of convertible debt, net of tax and offering costs	117,464	$ 1	117,463
Issuance of common stock under the 2006 Employee Stock Purchase Plan (the ESPP) (in shares)		258,000
Issuance of common stock under the 2006 Employee Stock Purchase Plan (the ESPP)	8,714		8,714
Exercise of common stock options (in shares)		2,564,000
Exercise of common stock options	71,190	$ 3	71,187
Excess tax benefit from stock option exercises	1,491		1,491
Conversion of convertible notes, net (in shares)		1,055,000
Conversion of convertible notes, net	21,324	$ 1	21,323
Restricted stock vested during the period, net (in shares)		253,000
Restricted stock vested during the period, net	(7,768)		(7,768)
Common stock held by Nonqualified Deferred Compensation Plan	(2,274)			(2,274)
Stock-based compensation	88,233		88,233
Ending Balance at Dec. 31, 2014	1,527,894	$ 149	2,359,744	(9,695)	27,466	(849,770)
Ending Balance (in shares) at Dec. 31, 2014		149,094,000
Net loss	(171,799)					(171,799)
Other comprehensive income (loss)	(6,433)				(6,433)
Issuance of common stock, net of offering costs (in shares)		9,775,000
Issuance of convertible debt, net of tax and offering costs	888,257	$ 10	888,247
Issuance of common stock under the 2006 Employee Stock Purchase Plan (the ESPP) (in shares)		185,000
Issuance of common stock under the 2006 Employee Stock Purchase Plan (the ESPP)	$ 9,957		9,957
Exercise of common stock options (in shares)	1,723,345	1,723,000
Exercise of common stock options	$ 53,088	$ 2	53,086
Excess tax benefit from stock option exercises	2,190		2,190
Conversion of convertible notes, net (in shares)		449,000
Conversion of convertible notes, net	9,112	$ 1	9,111
Restricted stock vested during the period, net (in shares)		300,000
Restricted stock vested during the period, net	(22,989)		(22,989)
Common stock held by Nonqualified Deferred Compensation Plan	(3,921)			(3,921)
Stock-based compensation	115,491		115,491
Ending Balance at Dec. 31, 2015	$ 2,400,847	$ 162	$ 3,414,837	$ (13,616)	$ 21,033	$ (1,021,569)
Ending Balance (in shares) at Dec. 31, 2015		161,526,000