Consolidated Statements of Stockholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		11 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Balance as of	$ 258,294	$ 242,877	$ 246,895	$ 258,294	$ 242,877	$ 246,895	$ 212,957
Balance as of (in Shares)	35,673,282	33,826,032		35,673,282	33,826,032
Net income				15,756	13,301	29,563
Auction Rate Securities valuation reserve adj.				140	270	160
Unrealized losses				34	(37)	104
Foreign exchange gain				408	1,381	1,361
Cash dividend				(35,664)
Exercise of stock options, including net excess tax benefit				14,232	4,630	15,597
Exercise of stock options, including net excess tax benefit (in Shares)			(1,452,245)	(1,151,884)	(685,417)
Repurchase of common shares					(38,472)	(31,527)
Repurchase of common shares (in Shares)					2,485,500	1,899,789
Shares purchased through ESPP				1,852	1,773	1,885
Shares purchased through ESPP (in Shares)				151,770	149,981	114,387
Stock-based compensation expense, net of forfeitures				18,642	13,123	16,803
Compensation expense for non-employee stock options	7,326	3,090		18,652	13,136	16,810
Common Stock [Member] | Non Employee [Member]
Compensation expense for non-employee stock options				17	13	(7)
Common Stock [Member]
Balance as of	194,079	159,336	178,269	194,079	159,336	178,269	175,518
Balance as of (in Shares)	35,673,282	33,826,032	35,063,033	35,673,282	33,826,032	35,063,033	35,165,316
Exercise of stock options, including net excess tax benefit				14,232	4,630	15,597
Exercise of stock options, including net excess tax benefit (in Shares)				1,151,884	685,417	1,452,245
Repurchase of common shares					(38,472)	(31,527)
Repurchase of common shares (in Shares)					(2,485,500)	(1,899,789)
Shares purchased through ESPP				1,852	1,773	1,885
Shares purchased through ESPP (in Shares)				151,770	149,981	114,387
Stock-based compensation expense, net of forfeitures				18,642	13,123	16,803
Release of restricted stock upon vesting (in Shares)				543,596	413,101	230,874
Retained Earnings [Member]
Balance as of	60,040	79,948	66,647	60,040	79,948	66,647	37,085
Net income				15,756	13,301	29,563
Cash dividend				(35,664)
Accumulated Other Comprehensive Income (Loss) [Member]
Balance as of	4,175	3,593	1,979	4,175	3,593	1,979	354
Auction Rate Securities valuation reserve adj.				140	270	160
Unrealized losses				34	(37)	104
Foreign exchange gain				408	1,381	1,361
Non Employee [Member]
Compensation expense for non-employee stock options				$ 17	$ 13	$ (7)