Consolidated Statements of Stockholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Treasury Shares	Additional paid-in capital	Accumulated other comprehensive loss	Retained Earnings
Balance at Dec. 31, 2012	$ 757,039	$ 163	$ (350,000)	$ 789,719	$ (2,975)	$ 320,132
Balance (in shares) at Dec. 31, 2012		65,114,000	16,042,000
Increase (Decrease) in Stockholders' Equity
Exercise of common stock options	3,300			3,300
Exercise of common stock options (in shares)		281,000
Conversion of senior convertible notes	11			11
Conversion of senior convertible notes (in shares)		1,000
Restricted stock vested (in shares)		34,000
Employee stock purchase plan	558			558
Employee stock purchase plan (in shares)		27,000
Share-based compensation	12,286			12,286
Other comprehensive loss	(826)				(826)
Stock option tax benefits	808			808
Net loss	(63,398)					(63,398)
Balance at Jun. 30, 2013	$ 709,778	$ 163	$ (350,000)	$ 806,682	$ (3,801)	$ 256,734
Balance (in shares) at Jun. 30, 2013		65,457,000	16,042,000