CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Earnings/(Deficit)
Balance, beginning of year at Dec. 31, 2012		$ 4	$ 652,110	$ 0	$ 39,172
Common stock (par value)
Issuance of common stock upon exercise of options and vesting of restricted stock units		1
Common stock repurchased and retired		(1)			(32,241)
Balance, end of year at Dec. 31, 2013		4	771,875	0	16,216
Balance, beginning of year at Dec. 31, 2012		4	652,110	0	39,172
Additional paid-in capital
Issuance of common stock upon exercise of options and vesting of restricted stock units			19,112
Stock based compensation, net of forfeitures			55,237
Accelerated share repurchase of common stock	$ 0
Tax benefit/(shortfall) of stock options			(2,957)
Equity component of the convertible note issuance, net			62,409
Purchase of convertible note hedge			63,510
Sale of warrants			43,560
Balance, end of year at Dec. 31, 2013		4	771,875	0	16,216
Accumulated other comprehensive income (loss), net of tax
Unrealized loss on investments, net of tax				0
Balance, beginning of year at Dec. 31, 2012		4	652,110	0	39,172
Accumulated earnings/(deficit)
Common stock repurchased and retired		(1)			(32,241)
Net income/(loss)	$ 9,285				9,285
Balance, end of year at Dec. 31, 2013		$ 4	771,875	0	16,216
Balance, beginning of year at Dec. 31, 2012		36,358,000
Number of shares
Issuance of common stock upon exercise of options and vesting of restricted stock units		2,540,000
Common stock repurchased and retired	(100,000)	(702,000)
Balance, end of year at Dec. 31, 2013	38,196,000	38,196,000
Accumulated earnings/(deficit)
Total stockholders' equity	$ 788,095
Issuance of common stock upon exercise of options and vesting of restricted stock units		$ 1
Common stock repurchased and retired		(1)			(88,814)
Balance, end of year at Dec. 31, 2014		4	838,313	(53)	(80,458)
Balance, beginning of year at Dec. 31, 2013		4	771,875	0	16,216
Additional paid-in capital
Issuance of common stock upon exercise of options and vesting of restricted stock units			3,243
Stock based compensation, net of forfeitures			63,358
Accelerated share repurchase of common stock	0
Tax benefit/(shortfall) of stock options			163
Equity component of the convertible note issuance, net			0
Purchase of convertible note hedge			0
Sale of warrants			0
Balance, end of year at Dec. 31, 2014		4	838,313	(53)	(80,458)
Accumulated other comprehensive income (loss), net of tax
Unrealized loss on investments, net of tax				(53)
Balance, end of year at Dec. 31, 2014	(53)
Balance, beginning of year at Dec. 31, 2013		4	771,875	0	16,216
Accumulated earnings/(deficit)
Common stock repurchased and retired		(1)			(88,814)
Net income/(loss)	$ (7,860)				(7,860)
Balance, end of year at Dec. 31, 2014		$ 4	838,313	(53)	(80,458)
Number of shares
Issuance of common stock upon exercise of options and vesting of restricted stock units		1,671,000
Common stock repurchased and retired	(2,000,000)	(1,961,000)
Balance, end of year at Dec. 31, 2014	37,906,000	37,906,000
Accumulated earnings/(deficit)
Total stockholders' equity	$ 757,806
Issuance of common stock upon exercise of options and vesting of restricted stock units		$ 1
Common stock repurchased and retired		(1)			(212,791)
Balance, end of year at Dec. 31, 2015		4	900,218	(68)	(294,092)
Balance, beginning of year at Dec. 31, 2014		4	838,313	(53)	(80,458)
Additional paid-in capital
Issuance of common stock upon exercise of options and vesting of restricted stock units			3,221
Stock based compensation, net of forfeitures			61,705
Accelerated share repurchase of common stock	(3,119)
Tax benefit/(shortfall) of stock options			(98)
Equity component of the convertible note issuance, net			0
Purchase of convertible note hedge			0
Sale of warrants			0
Balance, end of year at Dec. 31, 2015		4	900,218	(68)	(294,092)
Accumulated other comprehensive income (loss), net of tax
Unrealized loss on investments, net of tax				(15)
Balance, end of year at Dec. 31, 2015	(68)
Balance, beginning of year at Dec. 31, 2014		4	838,313	(53)	(80,458)
Accumulated earnings/(deficit)
Common stock repurchased and retired		(1)			(212,791)
Net income/(loss)	$ (843)				(843)
Balance, end of year at Dec. 31, 2015		$ 4	$ 900,218	$ (68)	$ (294,092)
Number of shares
Issuance of common stock upon exercise of options and vesting of restricted stock units		1,780,000
Common stock repurchased and retired	(4,900,000)	(4,909,000)
Balance, end of year at Dec. 31, 2015	34,777,000
Accumulated earnings/(deficit)
Total stockholders' equity	$ 606,062