Subsequent Events (Details) (Subsequent event, USD $)	1 Months Ended
	Feb. 28, 2014	Jan. 31, 2014
Common stock
Subsequent events
Common stock, dividends declared (in dollars per share)	$ 0.1821667	$ 0.1821667
Class E preferred stockholders
Subsequent events
Preferred stock, dividends declared (in dollars per share)	$ 0.140625	$ 0.140625
Class F preferred stockholders
Subsequent events
Preferred stock, dividends declared (in dollars per share)	$ 0.138021	$ 0.138021