Consolidated Statements of Shareholders' Equity and Comprehensive Income (USD $) In Thousands, except Share data	Total	Common Stock	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Comprehensive Income
Balance at Dec. 31, 2008	$ 208,406	$ 0	$ (2,244)	$ 210,650
Balance, shares at Dec. 31, 2008		67,308,899
Net income	16,294			16,294	16,294
Other comprehensive income, change in net unrealized losses from investments, net of tax	485		485		485
Comprehensive income					16,779
Share-based compensation	4,007	4,007
Payment of cash dividends	(8,888)			(8,888)
Repurchases of common stock	(32,448)	(292)		(32,156)
Repurchases of common stock, shares		(5,020,920)
Employee stock transactions	394	394
Employee stock transactions, shares		60,289
Tax effect of employee stock transactions	(2,899)	(2,899)
Balance at Dec. 31, 2009	185,351	1,210	(1,759)	185,900
Balance, shares at Dec. 31, 2009		62,348,268
Net income	50,708			50,708	50,708
Other comprehensive income, change in net unrealized losses from investments, net of tax	547		547		547
Comprehensive income					51,255
Share-based compensation	4,722	4,722
Payment of cash dividends	(8,646)			(8,646)
Repurchases of common stock	(16,053)	(10,543)		(5,510)
Repurchases of common stock, shares		(1,594,089)
Employee stock transactions	6,861	6,861
Employee stock transactions, shares		849,981
Tax effect of employee stock transactions	151	151
Balance at Dec. 31, 2010	223,641	2,401	(1,212)	222,452
Balance, shares at Dec. 31, 2010	61,604,160	61,604,160
Net income	34,016			34,016	34,016
Other comprehensive income, change in net unrealized losses from investments, net of tax	325		325		325
Comprehensive income					34,341
Share-based compensation	5,886	5,886
Payment of cash dividends	(9,358)			(9,358)
Repurchases of common stock	(20,253)	(20,253)
Repurchases of common stock, shares		(1,853,962)
Employee stock transactions	12,040	12,040
Employee stock transactions, shares		1,293,571
Tax effect of employee stock transactions	195	195
Purchases of common stock for withholding taxes on vested restricted stock	(63)	(63)
Purchases of common stock for withholding taxes on vested restricted stock, shares		(5,262)
Balance at Dec. 31, 2011	$ 246,429	$ 206	$ (887)	$ 247,110
Balance, shares at Dec. 31, 2011	61,038,507	61,038,507