Consolidated Statements of Changes in Stockholders Equity (Unaudited) (USD $) In Thousands, unless otherwise specified	Total	Common stock	Retained earnings	Accumulated other comprehensive income
Beginning Balance at Dec. 31, 2012	$ 751,186	$ 271,335	$ 463,860	$ 15,991
Comprehensive income:
Net income	41,549	0	41,549	0
Other comprehensive income, net of tax	(25,030)	0	0	(25,030)
Common stock transactions:
Common shares purchased and retired 349,930 and 25,677 in 2014 and 2013, respectively	(448)	(448)	0	0
Common shares issued 24,581 in 2014 and 26,096 in 2013	0	0	0	0
Non-vested common shares issued 147,876 and 108,873 in 2014 and 2013 respectively	0	0	0	0
8,647 and 10,138 non-vested common shares forfeited in 2014 and 2013 respectively	0	0	0	0
286,069 and 446,404 stock options exercised, net of 160,377 and 150,290 shares tendered in payment of option price and income tax withholding amounts in 2014 and 2013 respectively	5,799	5,799	0	0
Tax benefit of stock-based compensation	524	524	0	0
Stock-based compensation expense	2,022	2,022	0	0
Cash dividends declared:
Common ($0.32 per share) in 2014 and ($0.13 per share) in 2013	(5,648)	0	(5,648)	0
Ending Balance at Jun. 30, 2013	769,954	279,232	499,761	(9,039)
Beginning Balance at Dec. 31, 2013	801,581	285,535	532,087	(16,041)
Comprehensive income:
Net income	42,470	0	42,470	0
Other comprehensive income, net of tax	10,401	0	0	10,401
Common stock transactions:
Common shares purchased and retired 349,930 and 25,677 in 2014 and 2013, respectively	(8,764)	(8,764)	0	0
Common shares issued 24,581 in 2014 and 26,096 in 2013	0	0	0	0
Non-vested common shares issued 147,876 and 108,873 in 2014 and 2013 respectively	0	0	0	0
8,647 and 10,138 non-vested common shares forfeited in 2014 and 2013 respectively	0	0	0	0
286,069 and 446,404 stock options exercised, net of 160,377 and 150,290 shares tendered in payment of option price and income tax withholding amounts in 2014 and 2013 respectively	3,547	3,547	0	0
Tax benefit of stock-based compensation	1,225	1,225	0	0
Stock-based compensation expense	2,154	2,154	0	0
Cash dividends declared:
Common ($0.32 per share) in 2014 and ($0.13 per share) in 2013	(14,088)	0	(14,088)	0
Ending Balance at Jun. 30, 2014	$ 838,526	$ 283,697	$ 560,469	$ (5,640)