Common Stock Common Stock Sold (Details) (USD $)	0 Months Ended	9 Months Ended	12 Months Ended
	Nov. 14, 2011	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011	Oct. 02, 2012
Class of Stock [Line Items]
Dividend Ratio Class E					4.786
Sale of Stock, Number of Shares Issued in Transaction	21,588	5,120,355
Sale of Stock, Consideration Received on Transaction	$ 200,000		$ 88,886,000	$ 617,000
Class E Shares [Member]
Class of Stock [Line Items]
Sale of Stock, Number of Shares Issued in Transaction			5,202,625	66,568
Sale of Stock, Consideration Received on Transaction			50,794,000	617,000
Class A Shares [Member]
Class of Stock [Line Items]
Sale of Stock, Number of Shares Issued in Transaction			3,612,169	0
Sale of Stock, Consideration Received on Transaction			37,035,000	0
Class M Shares [Member]
Class of Stock [Line Items]
Sale of Stock, Number of Shares Issued in Transaction			104,282	0
Sale of Stock, Consideration Received on Transaction			$ 1,057,000	$ 0