Consolidated Statements of Stockholders' Equity (Parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Common stock transactions:
Stock options exercised	1,166,507
Common stock
Common stock transactions:
Common shares purchased and retired	25,677	18,351	17,926
Common shares issued	26,096	23,991	15,440
Non-vested common shares issued	120,873	122,912	130,904
Non-vested common shares forfeited	30,648	15,232	27,963
Stock options exercised	774,096	192,829	83,025
Shares tendered in payment of option price and income tax withholding amounts	392,411	183,805	174,583
Preferred Stock Including Additional Paid in Capital [Member]
Common stock transactions:
Stock Redeemed or Called During Period, Shares	0.00	5,000.00	0.00
Retained Earnings
Cash dividends declared:
Common (in dollars per share)	$ 0.41	$ 0.61	$ 0.45
Preferred (in dollars per share)	0.00%	6.75%	6.75%