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, 2011	$ 771,020	$ 50,000	$ 266,842	$ 435,144	$ 19,034
Comprehensive income:
Net income	12,214	0	0	12,214	0
Other comprehensive income, net of tax	460	0	0	0	460
Common stock transactions:
Common shares purchased and retired 25,677 and 17,904 in 2013 and 2012 respectively	(256)	0	(256)	0	0
Common shares issued 2,358 in 2012	0	0	0	0	0
Non-vested common shares issued 108,873 and 122,912 in 2013 and 2012 respectively	0	0	0	0	0
1,815 and 1,556 non-vested common shares forfeited in 2013 and 2012 respectively	0	0	0	0	0
243,238 and 100,991 stock options exercised, net of 87,933 and 37,397 shares tendered in payment of option price and income tax withholding amounts in 2013 and 2012 respectively	1,068	0	1,068	0	0
Tax benefit of stock-based compensation	114	0	114	0	0
Stock-based compensation expense	643	0	643	0	0
Cash dividends declared:
Common ($0.12) per share in 2012	(5,135)	0	0	(5,135)	0
Preferred (6.75%) per share in 2012	(853)	0	0	(853)	0
Ending Balance at Mar. 31, 2012	779,275	50,000	268,411	441,370	19,494
Beginning Balance at Dec. 31, 2012	751,186	0	271,335	463,860	15,991
Comprehensive income:
Net income	20,044	0	0	20,044	0
Other comprehensive income, net of tax	(3,451)	0	0	0	(3,451)
Common stock transactions:
Common shares purchased and retired 25,677 and 17,904 in 2013 and 2012 respectively	(448)	0	(448)	0	0
Non-vested common shares issued 108,873 and 122,912 in 2013 and 2012 respectively	0	0	0	0	0
1,815 and 1,556 non-vested common shares forfeited in 2013 and 2012 respectively	0	0	0	0	0
243,238 and 100,991 stock options exercised, net of 87,933 and 37,397 shares tendered in payment of option price and income tax withholding amounts in 2013 and 2012 respectively	3,145	0	3,145	0	0
Tax benefit of stock-based compensation	202	0	202	0	0
Stock-based compensation expense	695	0	695	0	0
Ending Balance at Mar. 31, 2013	$ 771,373	$ 0	$ 274,929	$ 483,904	$ 12,540