CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $) In Thousands, unless otherwise specified	Total	Common Stock	Shares Held Under Employee Participation Plan	Additional Paid-in Capital	Accumulated Other Comprehensive Income	Accumulated Earnings
Balance at Dec. 31, 2011	$ 900,987	$ 532	$ (469)	$ 497,919	$ 31,353	$ 371,652
Balance (in shares) at Dec. 31, 2011		53,183
Increase (Decrease) in Stockholders' Equity
Net income	32,015					32,015
Total other comprehensive income	15,180				15,180
Stock-based compensation	2,141			2,141
Stock-based compensation (in shares)		49
Issuance of restricted shares, net of shares remitted	(1,026)			(1,026)
Issuance of restricted shares, net of shares remitted (in shares)		(15)
Exercise of stock options	30	1		29
Exercise of stock options (in shares)		8
Net tax benefit on exercise of stock options	713			713
Employee stock purchase plan	1,238			1,238
Employee stock purchase plan (in shares)		31
Balance at Mar. 31, 2012	$ 951,278	$ 533	$ (469)	$ 501,014	$ 46,533	$ 403,667
Balance (in shares) at Mar. 31, 2012		53,256