Subsequent Events (Details) (USD $)	6 Months Ended	12 Months Ended	53 Months Ended			1 Months Ended	6 Months Ended		12 Months Ended	0 Months Ended	1 Months Ended	53 Months Ended	0 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013	Jul. 03, 2013	Jul. 02, 2013	Jun. 30, 2013 PE Investment II	Jun. 30, 2013 PE Investment II	Jun. 30, 2013 First mortgage loans	Dec. 31, 2012 First mortgage loans	Aug. 06, 2013 Subsequent event	Jul. 31, 2013 Subsequent event	Jul. 02, 2013 Subsequent event	Jul. 02, 2013 Subsequent event PE Investment II	Jun. 30, 2013 Subsequent event First mortgage loan item	Jun. 30, 2013 Subsequent event Mezzanine loan item
Offering Proceeds
Gross proceeds from Total Offering												$ 1,128,400,000
Distribution Reinvestment Plan
Shares issued representing all remaining shares available pursuant to the DRP	1,300,000	1,100,000	2,900,000									300,000
Common stock issued after filing a registration statement with the SEC, for issuance pursuant to the DRP (in shares)				15,000,000	7,600,000							15,000,000
Distributions
Daily cash distribution accrued per share (in dollars per share)	$ 0.002185792									$ 0.002191781
Annual distribution rate (as a percent)	8.00%									8.00%
Share Repurchases
Number of shares repurchased	300,000	100,000									100,000
Total amount of shares repurchased	2,675,000	1,371,000									1,200,000
Repurchase price paid per share (in dollars per share)	$ 9.50	$ 9.69									$ 9.80
PE Investment II
Amount funded, excluding adjustments for distributions and contributions since September 30, 2012							76,500,000						76,500,000
Amount deposited for proportionate interest						50,000,000	50,000,000
New Investments
Principal Amount	945,910,000	543,619,000	945,910,000					856,160,000	486,992,000
Description of variable rate	LIBOR	LIBOR						LIBOR	LIBOR
Number of loans originated														1	1
Principal amount	$ 350,530,000	$ 250,980,000	$ 350,530,000											$ 27,800,000	$ 66,500,000