Consolidated Statements Of Stockholders' Equity (USD $) In Thousands, except Share data	Preferred Stock [Member]	Common Stock [Member]	Treasury Shares [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]	Total
Balance, value at Dec. 31, 2011		$ 159	$ (169,661)	$ 749,519	$ (3,414)	$ 314,521	$ 891,124
Balance, shares at Dec. 31, 2011		70,568,000	9,159,000
Exercise of common stock options, shares		716,000
Exercise of common stock options, value		2		5,342			5,344
Restricted stock vested		27,000
Employee stock purchase plan, shares		13,000
Employee stock purchase plan, value				214			214
Share-based compensation, shares
Share-based compensation, value				4,904			4,904
Other comprehensive income					1,005		1,005
Repurchase of shares, shares		(1,606,000)	1,606,000
Repurchase of shares, value			(49,996)				(49,996)
Stock option tax benefits				4,827			4,827
Net income						19,991	19,991
Balance, value at Mar. 31, 2012		$ 161	$ (219,657)	$ 764,806	$ (2,409)	$ 334,512	$ 877,413
Balance, shares at Mar. 31, 2012		69,718,000	10,765,000