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, 2013	$ 801,581	$ 285,535	$ 532,087	$ (16,041)
Comprehensive income:
Net income	21,393	0	21,393	0
Other comprehensive income, net of tax	8,682	0	0	8,682
Common stock transactions:
Common shares purchased and retired 588,409 and 124,867 in 2015 and 2014, respectively	(3,159)	(3,159)	0	0
Non-vested common shares issued 156,956 and 147,876 in 2015 and 2014 respectively	0	0	0	0
838 and 3,782 non-vested common shares forfeited in 2015 and 2014 respectively	0	0	0	0
73,344 and 215,805 stock options exercised, net of 22,042 and 152,131 shares tendered in payment of option price and income tax withholding amounts in 2015 and 2014 respectively	2,476	2,476	0	0
Tax benefit of stock-based compensation	989	989	0	0
Stock-based compensation expense	712	712	0	0
Cash dividends declared:
Common ($0.20 per share) in 2015 and ($0.16 per share) in 2014	(7,036)	0	(7,036)	0
Ending Balance at Mar. 31, 2014	825,638	286,553	546,444	(7,359)
Beginning Balance at Dec. 31, 2014	908,924	323,596	587,862	(2,534)
Comprehensive income:
Net income	20,980	0	20,980	0
Other comprehensive income, net of tax	6,713	0	0	6,713
Common stock transactions:
Common shares purchased and retired 588,409 and 124,867 in 2015 and 2014, respectively	(15,264)	(15,264)	0	0
Non-vested common shares issued 156,956 and 147,876 in 2015 and 2014 respectively	0	0	0	0
838 and 3,782 non-vested common shares forfeited in 2015 and 2014 respectively	0	0	0	0
73,344 and 215,805 stock options exercised, net of 22,042 and 152,131 shares tendered in payment of option price and income tax withholding amounts in 2015 and 2014 respectively	900	900	0	0
Tax benefit of stock-based compensation	480	480	0	0
Stock-based compensation expense	832	832	0	0
Cash dividends declared:
Common ($0.20 per share) in 2015 and ($0.16 per share) in 2014	(9,115)	0	(9,115)	0
Ending Balance at Mar. 31, 2015	$ 914,450	$ 310,544	$ 599,727	$ 4,179