Consolidated Statements of Changes in Stockholders Equity (Unaudited) (USD $) In Thousands, unless otherwise specified	Total	Preferred stock	Common stock	Retained earnings	Accumulated other comprehensive income
Beginning Balance at Dec. 31, 2010	$ 736,802	$ 50,000	$ 264,174	$ 413,253	$ 9,375
Comprehensive income:
Net income	19,360	0	0	19,360	0
Other comprehensive income, net of tax	13,022	0	0	0	13,022
Common stock transactions:
Common shares purchased and retired 17,981 and 14,112 in 2012 and 2011 respectively	(193)	0	(193)	0	0
Common shares issued 23,973 and 14,692 in 2012 and 2011 respectively	195	0	195	0	0
Non-vested common shares issued 122,912 and 130,904 in 2012 and 2011 respectively	0	0	0	0	0
3,193 and 17,544 non-vested common shares forfeited in 2012 and 2011 respectively	(89)	0	(89)	0	0
Non-vested liability awards vesting during period	195	0	195	0	0
118,865 and 50,287 stock options exercised, net of 39,667 and 106,185 shares tendered in payment of option price and income tax withholding amounts in 2012 and 2011 respectively	102	0	102	0	0
Tax benefit of stock-based compensation	224	0	224	0	0
Stock-based compensation expense	1,031	0	1,031	0	0
Cash dividends declared:
Common ($0.24 and $0.225 per share in 2012 and 2011 respectively)	(9,607)	0	0	(9,607)	0
Preferred (6.75% per share in 2012 and 2011)	(1,697)	0	0	(1,697)	0
Ending Balance at Jun. 30, 2011	759,345	50,000	265,639	421,309	22,397
Beginning Balance at Dec. 31, 2011	771,020	50,000	266,842	435,144	19,034
Comprehensive income:
Net income	25,224	0	0	25,224	0
Other comprehensive income, net of tax	(769)	0	0	0	(769)
Common stock transactions:
Common shares purchased and retired 17,981 and 14,112 in 2012 and 2011 respectively	(257)	0	(257)	0	0
Common shares issued 23,973 and 14,692 in 2012 and 2011 respectively	0	0	0	0	0
Non-vested common shares issued 122,912 and 130,904 in 2012 and 2011 respectively	0	0	0	0	0
3,193 and 17,544 non-vested common shares forfeited in 2012 and 2011 respectively	0	0	0	0	0
118,865 and 50,287 stock options exercised, net of 39,667 and 106,185 shares tendered in payment of option price and income tax withholding amounts in 2012 and 2011 respectively	1,263	0	1,263	0	0
Tax benefit of stock-based compensation	126	0	126	0	0
Stock-based compensation expense	1,724	0	1,724	0	0
Cash dividends declared:
Common ($0.24 and $0.225 per share in 2012 and 2011 respectively)	(10,290)	0	0	(10,290)	0
Preferred (6.75% per share in 2012 and 2011)	(1,706)	0	0	(1,706)	0
Ending Balance at Jun. 30, 2012	$ 786,335	$ 50,000	$ 269,698	$ 448,372	$ 18,265