Consolidated Statements of Stockholders' Equity and Comprehensive Income (USD $) In Thousands, unless otherwise specified	Total	Capital Stock, Common	Additional Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Loss
Balance at Dec. 31, 2008	$ 360,039	$ 942	$ 439	$ 367,281	$ 0	$ (8,623)
Comprehensive income:
Net income	56,949	0	0	56,949	0	0
Unrealized loss on available-for-sale securities, net of tax	3,297	0	0	0	0	3,297
Total comprehensive income	60,246
Dividends on common stock	(7,255)	0	0	(7,255)	0	0
Repurchases of common stock	(45,360)	(35)	0	(45,325)	0	0
Stock-based Compensation	0
Balance at Dec. 31, 2009	367,670	907	439	371,650	0	(5,326)
Comprehensive income:
Net income	62,216	0	0	62,216	0	0
Unrealized loss on available-for-sale securities, net of tax	2,245	0	0	0	0	2,245
Total comprehensive income	64,461
Dividends on common stock	(97,944)	0	0	(97,944)	0	0
Stock-based Compensation	0
Balance at Dec. 31, 2010	334,187	907	439	335,922	0	(3,081)
Comprehensive income:
Net income	69,932	0	0	69,932	0	0
Unrealized loss on available-for-sale securities, net of tax	0	0	0	0	0	0
Total comprehensive income	69,932
Dividends on common stock	(7,148)	0	0	(7,148)	0	0
Repurchases of common stock	(56,350)	0	0	0	(56,350)	0
Stock-based Compensation	150	0	150	0	0	0
Balance at Dec. 31, 2011	$ 340,771	$ 907	$ 589	$ 398,706	$ (56,350)	$ (3,081)