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	1,305			1,305
Exercise of common stock options (in shares)		119,000
Restricted stock vested (in shares)		34,000
Employee stock purchase plan	300			300
Employee stock purchase plan (in shares)		15,000
Share-based compensation	5,992			5,992
Other comprehensive loss	(520)				(520)
Stock option tax benefits	417			417
Net loss	(63,997)					(63,997)
Balance at Mar. 31, 2013	$ 700,536	$ 163	$ (350,000)	$ 797,733	$ (3,495)	$ 256,135
Balance (in shares) at Mar. 31, 2013		65,282,000	16,042,000