CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $) In Thousands, unless otherwise specified	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Earnings [Member]	Total
Balance at Dec. 31, 2008	$ 2	$ 203,902	$ (17,102)
Balance (in shares) at Dec. 31, 2008	25,138
Common stock (par value)
Issuance of common stock in connection with acquisition and upon exercise of options and vesting of restricted stock units	1
Issuance of common stock upon exercise of options and vesting of restricted stock units (in shares)	771
Issuance of common stock in connection with acquisition (in shares)	0
Additional paid-in capital
Issuance of common stock upon exercise of options and vesting of restricted stock units		1,699
Stock based compensation, net of estimated forfeiture		15,844
Issuance of common stock in connection with acquisition		0
Tax benefit of stock options		4,965		4,965
Accumulated earnings (deficit)
Net income			5,853	5,853
Total stockholders' equity				215,164
Balance at Dec. 31, 2009	3	226,410	(11,249)
Balance (in shares) at Dec. 31, 2009	25,909
Common stock (par value)
Issuance of common stock in connection with acquisition and upon exercise of options and vesting of restricted stock units	0
Issuance of common stock upon exercise of options and vesting of restricted stock units (in shares)	2,048
Issuance of common stock in connection with acquisition (in shares)	0
Additional paid-in capital
Issuance of common stock upon exercise of options and vesting of restricted stock units		14,703
Stock based compensation, net of estimated forfeiture		16,640
Issuance of common stock in connection with acquisition		0
Tax benefit of stock options		5,973		5,973
Accumulated earnings (deficit)
Net income			17,127	17,127
Total stockholders' equity				269,607
Balance at Dec. 31, 2010	3	263,726	5,878
Balance (in shares) at Dec. 31, 2010	27,957			27,957
Common stock (par value)
Issuance of common stock in connection with acquisition and upon exercise of options and vesting of restricted stock units	1
Issuance of common stock upon exercise of options and vesting of restricted stock units (in shares)	2,882
Issuance of common stock in connection with acquisition (in shares)	4,000
Additional paid-in capital
Issuance of common stock upon exercise of options and vesting of restricted stock units		22,277
Stock based compensation, net of estimated forfeiture		34,351
Issuance of common stock in connection with acquisition		260,322
Tax benefit of stock options		8,391		8,391
Accumulated earnings (deficit)
Net income			14,048	14,048
Total stockholders' equity				608,997
Balance at Dec. 31, 2011	$ 4	$ 589,067	$ 19,926
Balance (in shares) at Dec. 31, 2011	34,839			34,839