Subsequent Events (Details) (USD $)	3 Months Ended			12 Months Ended			0 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Feb. 28, 2012 Dividend Declared [Member]	Feb. 28, 2012 Dividend Paid [Member]
Subsequent Event [Line Items]
Common Stock, Dividends, Per Share, Declared							$ 0.25
Common Stock, Dividends, Per Share, Cash Paid	$ 0.20	$ 0.20	$ 0.20	$ 0.60	$ 0.50	$ 0.50		$ 0.25