Consolidated Statements of Stockholders' Equity (Parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Common stock transactions:
Stock options exercised	376,634
Common stock
Common stock transactions:
Common shares purchased and retired	18,351	17,926	246,596
Common shares issued	23,991	15,440	11,506,503
Non-vested common shares issued	122,912	130,904	117,140
Non-vested common shares forfeited	15,232	27,963	18,821
Stock options exercised	192,829	83,025	92,880
Shares tendered in payment of option price and income tax withholding amounts	183,805	174,583	111,792
Retained Earnings
Cash dividends declared:
Common (in dollars per share)	0.61	0.45	0.45
Preferred (in dollars per share)	6.75%	6.75%	6.75%