Stockholders' Equity (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	1 Months Ended						6 Months Ended	12 Months Ended	53 Months Ended
	Jun. 30, 2013	May 31, 2013	Apr. 30, 2013	Mar. 31, 2013	Feb. 28, 2013	Jan. 31, 2013	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013	Jul. 03, 2013	Jul. 02, 2013
Common Stock
Number of shares of common stock issued pursuant to the Total Primary Offering							51.5	43.4	107.6
Gross proceeds from issuance of common stock							$ 512,800,000	$ 433,000,000	$ 1,072,900,000
Distribution Reinvestment Plan
Initial purchase price per share under the DRP (in dollars per share)							$ 9.50
Price of shares issued as a percentage of estimated value per share							95.00%
Period within which the company expects to establish an estimated value per share							18 months
Selling commissions or dealer manager fees that will be paid for sales under DRP							0
Notice period served by board of directors to amend or terminate DRP							10 days
Shares issued pursuant to DRP							1.3	1.1	2.9
Total proceeds from sale of shares pursuant to DRP							12,509,000	10,305,000	27,400,000
Common stock issued after filing a registration statement with the SEC, for issuance pursuant to the DRP (in shares)										15.0	7.6
Distributions
Daily amount of distribution accrued per share (in dollars per share)							$ 0.002185792
Annual distribution rate (as a percent)							8.00%
Cash	3,901,000	3,620,000	3,173,000	2,909,000	2,378,000	2,441,000	32,329,000	27,922,000
DRP	3,067,000	2,751,000	2,352,000	2,163,000	1,778,000	1,795,000
Total	6,968,000	6,371,000	5,525,000	5,072,000	4,156,000	4,236,000
Share Repurchase Program
Holding period of shares required for repurchase							1 year
Number of shares repurchased							0.3	0.1
Total amount of shares repurchased							$ 2,675,000	$ 1,371,000
Repurchase price paid per share (in dollars per share)							$ 9.50	$ 9.69