CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Common Stock [Member] Pfizer Notes Due 2014	Common Stock [Member] 4.75% Convertible Senior Notes due 2015	Common Stock [Member]	Additional Paid-in Capital [Member] Pfizer Notes Due 2014	Additional Paid-in Capital [Member] 4.75% Convertible Senior Notes due 2015	Additional Paid-in Capital [Member] 1.25% Convertible Senior Notes due 2020	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]	Pfizer Notes Due 2014	4.75% Convertible Senior Notes due 2015	1.25% Convertible Senior Notes due 2020	Total
Balances at Dec. 31, 2012			$ 133				$ 1,476,922	$ 1,878	$ (1,653,890)				$ (174,957)
Increase (Decrease) in Stockholders' Equity
Issuance of 5,220,474, 7,044,844 and 6,898,551 shares of Common Stock upon exercise of stock options and restricted stock units and 194,453, 193,657 and 390,000 shares of Common Stock under the ESPP for the years ended 2015, 2014 and 2013, respectively			7				73,150						73,157
Issuance of shares of Common Stock upon conversion of Pfizer Note and conversion of Convertible Senior Notes	$ 1	$ 22		$ 9,372	$ 154,316					$ 9,373	$ 154,338
Reclassification to additional paid in capital in connection with repurchase of $117.3 million aggregate principal of 4.75% convertible senior notes due 2015							(381,405)						(381,405)
Equity component of 0.375% convertible senior notes due 2018 and 1.25% convertible senior notes due 2020							170,806						170,806
Excess tax benefit (provision) from stock based compensation							214						214
Stock compensation expense							38,398						38,398
Other comprehensive (loss)								115					115
Net income (loss)									(83,147)				(83,147)
Balances at Dec. 31, 2013			163				1,541,773	1,993	(1,737,037)				(193,108)
Increase (Decrease) in Stockholders' Equity
Issuance of 5,220,474, 7,044,844 and 6,898,551 shares of Common Stock upon exercise of stock options and restricted stock units and 194,453, 193,657 and 390,000 shares of Common Stock under the ESPP for the years ended 2015, 2014 and 2013, respectively			7				92,837						92,844
Issuance of shares of Common Stock upon conversion of Pfizer Note and conversion of Convertible Senior Notes		1			5,160						5,161
Excess tax benefit (provision) from stock based compensation							(22)						(22)
Stock compensation expense							62,156						62,156
Other comprehensive (loss)								(178)					(178)
Net income (loss)									(48,481)				(48,481)
Balances at Dec. 31, 2014			171				1,701,904	1,815	(1,785,518)				(81,628)
Increase (Decrease) in Stockholders' Equity
Issuance of 5,220,474, 7,044,844 and 6,898,551 shares of Common Stock upon exercise of stock options and restricted stock units and 194,453, 193,657 and 390,000 shares of Common Stock under the ESPP for the years ended 2015, 2014 and 2013, respectively			5				86,755						86,760
Issuance of shares of Common Stock upon conversion of Pfizer Note and conversion of Convertible Senior Notes		$ 11			$ 88,963	$ 180					$ 88,974	$ 180
Issuance of 2,017 shares of Common Stock for services rendered							218						218
Excess tax benefit (provision) from stock based compensation							2,872						2,872
Stock compensation expense							69,872						69,872
Other comprehensive (loss)								(2,624)					(2,624)
Net income (loss)									6,531				6,531
Balances at Dec. 31, 2015			$ 187				$ 1,950,764	$ (809)	$ (1,778,987)				$ 171,155