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	31,281	0	0	31,281	0
Other comprehensive income, net of tax	14,707	0	0	0	14,707
Common stock transactions:
Common shares purchased and retired 18,333 and 14,464 in 2012 and 2011 respectively	(197)	0	(197)	0	0
Common shares issued 23,973 and 15,440 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 20,039 non-vested common shares forfeited in 2012 and 2011 respectively	(101)	0	(101)	0	0
Non-vested liability awards vesting during period	195	0	195	0	0
144,346 and 67,197 stock options exercised, net of 102,213 and 114,211 shares tendered in payment of option price and income tax withholding amounts in 2012 and 2011 respectively	272	0	272	0	0
Tax benefit of stock-based compensation	204	0	204	0	0
Stock-based compensation expense	1,770	0	1,770	0	0
Cash dividends declared:
Common ($0.36 and $0.3375 per share in 2012 and 2011 respectively)	(14,419)	0	0	(14,419)	0
Preferred (6.75% per share in 2012 and 2011)	(2,559)	0	0	(2,559)	0
Ending Balance at Sep. 30, 2011	767,955	50,000	266,317	427,556	24,082
Beginning Balance at Dec. 31, 2011	771,020	50,000	266,842	435,144	19,034
Comprehensive income:
Net income	41,379	0	0	41,379	0
Other comprehensive income, net of tax	(223)	0	0	0	(223)
Common stock transactions:
Common shares purchased and retired 18,333 and 14,464 in 2012 and 2011 respectively	(262)	0	(262)	0	0
Common shares issued 23,973 and 15,440 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 20,039 non-vested common shares forfeited in 2012 and 2011 respectively	0	0	0	0	0
144,346 and 67,197 stock options exercised, net of 102,213 and 114,211 shares tendered in payment of option price and income tax withholding amounts in 2012 and 2011 respectively	1,326	0	1,326	0	0
Tax benefit of stock-based compensation	296	0	296	0	0
Stock-based compensation expense	2,351	0	2,351	0	0
Cash dividends declared:
Common ($0.36 and $0.3375 per share in 2012 and 2011 respectively)	(15,448)	0	0	(15,448)	0
Preferred (6.75% per share in 2012 and 2011)	(2,569)	0	0	(2,569)	0
Ending Balance at Sep. 30, 2012	$ 797,870	$ 50,000	$ 270,553	$ 458,506	$ 18,811