Consolidated Statements of Stockholders' Equity (Deficit) (Unaudited) (USD $) In Thousands, except Share data	Total	Common Stock Par Value $0.01 Per Share	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning Balance at Dec. 31, 2010	$ 52,545	$ 255	$ 142,508	$ (1,736)	$ (88,482)
Beginning Balance, shares at Dec. 31, 2010		25,452
Issuance of common stock for exercise of stock options and vesting of RSUs, net of effect of early exercises and withholding tax	2,815	14	2,801
Issuance of common stock for exercise of stock options and vesting of RSUs, net of effect of early exercises and withholding tax, shares		1,436
Stock-based compensation expense	2,723		2,723
Equity component of convertible senior notes issuance	39,151		39,151
Tax windfall benefits on exercises of stock options	77		77
Foreign currency translation adjustment	(271)			(268)
Unrealized gain on investments	3
Net income	19,486				19,486
Ending Balance at Jun. 30, 2011	116,529	269	187,260	(2,004)	(68,996)
Ending Balance, shares at Jun. 30, 2011		26,888
Beginning Balance at Dec. 31, 2011	133,243	271	191,714	(2,557)	(56,185)
Beginning Balance, shares at Dec. 31, 2011		27,106
Issuance of common stock for exercise of stock options and vesting of RSUs, net of effect of early exercises and withholding tax	90	5	85
Issuance of common stock for exercise of stock options and vesting of RSUs, net of effect of early exercises and withholding tax, shares		475
Stock-based compensation expense	6,972		6,972
Tax windfall benefits on exercises of stock options	(61)		(61)
Foreign currency translation adjustment	(690)			(690)
Unrealized gain on investments	21			21
Net income	4,057				4,057
Ending Balance at Jun. 30, 2012	$ 143,632	$ 276	$ 198,710	$ (3,226)	$ (52,128)
Ending Balance, shares at Jun. 30, 2012		27,581