Common Stock and Dividends (Details) (USD $)	0 Months Ended					1 Months Ended	3 Months Ended
	Apr. 19, 2013	Apr. 09, 2013	Feb. 28, 2013	Oct. 15, 2012	Apr. 20, 2012	Apr. 30, 2009	Mar. 31, 2013	May 06, 2013
Common Stock and Dividends
Series A cumulative perpetual preferred shares, outstanding							216,000
Warrants to purchase entity's common stock (in shares)							1,326,238
Warrants, exercise price (in dollars per share)							$ 24.43
Percentage of aggregate common stock investment on exercise of warrant to Senior Preferred Stock investment							15.00%
Warrants, term							10 years
Number of warrants exercised							0
Cash dividends paid to common shareholders (in dollars per share)	$ 0.20			$ 0.20	$ 0.20
Repurchase of common stock, authorized amount		$ 40,000,000	$ 40,000,000			$ 40,000,000
Period of repurchase of common stock			12 months			12 months
Cumulative number of shares repurchased under all stock repurchase programs								7,843,293
Cumulative cost of shares repurchased under all stock repurchase programs								$ 237,536,000