Redemption of Preferred Stock (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended	9 Months Ended	1 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014 Class E preferred stockholders	Sep. 30, 2014 Class E preferred stockholders	Dec. 31, 2006 Class E preferred stockholders	Dec. 07, 2011 Class E preferred stockholders
Distributions paid and payable
Preferred stock redeemed (in shares)			8,800,000
Preferred stock, dividend rate (as a percent)			6.75%		6.75%
Preferred stock, redemption price per share (in dollars per share)			$ 25.00	$ 25.00		$ 25.00
Preferred shares subject to mandatory redemption	$ 220,000	$ 220,000	$ 220,000	$ 220,000
Excess of redemption value over carrying value of preferred shares subject to redemption	$ 6,015	$ 6,015		$ 6,000