CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (USD $) In Thousands, unless otherwise specified	Total	Common Stock	Treasury Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings
Balance at Dec. 31, 2009	$ 444,885	$ 347	$ (252,380)	$ 520,852	$ 8,905	$ 167,161
Balance, shares at Dec. 31, 2009		34,740	(6,136)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	65,669					65,669
Total comprehensive income (loss)	(10,700)				(10,700)
Issuance of common stock through employee benefit plans	10,618	8		10,610
Issuance of common stock through employee benefit plans, shares		787
Share-based compensation	20,769			20,769
Repurchse of common stock	(31,278)		(31,278)
Repurchase of common stock, shares			(858)
Balance at Dec. 31, 2010	499,963	355	(283,658)	552,231	(1,795)	232,830
Balance, shares at Dec. 31, 2010		35,527	(6,994)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	27,989					27,989
Total comprehensive income (loss)	(7,298)				(7,298)
Proceeds from equity component of convertible notes	43,170			43,170
Proceeds from sale of stock purchase warrants	28,451			28,451
Purchase of option hedge on convertible notes	(42,895)			(42,895)
Equity portion of convertible notes issuance costs	(1,334)			(1,334)
Issuance of common stock through employee benefit plans	376	2		374
Issuance of common stock through employee benefit plans, shares		207
Share-based compensation	27,679			27,679
Repurchse of common stock	(83,463)		(83,463)
Repurchase of common stock, shares	(1,909)		(1,909)
Balance at Dec. 31, 2011	492,638	357	(367,121)	607,676	(9,093)	260,819
Balance, shares at Dec. 31, 2011		35,734	(8,903)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	41,204					41,204
Total comprehensive income (loss)	4,296				4,296
Issuance of common stock through employee benefit plans	251	1		250
Issuance of common stock through employee benefit plans, shares		9
Share-based compensation	(20,614)	11		(20,625)
Share-based compensation, shares		1,109
Repurchse of common stock	0		0
Repurchase of common stock, shares	0		0
Balance at Dec. 31, 2012	$ 517,775	$ 369	$ (367,121)	$ 587,301	$ (4,797)	$ 302,023
Balance, shares at Dec. 31, 2012		36,852	(8,903)