Stockholders' Equity - Common Stock from Primary Offering (Narrative) (Details) - USD ($) shares in Thousands		12 Months Ended		33 Months Ended
	Mar. 28, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016
Class of Stock [Line Items]
Common stock offering		$ 7,697,289	$ 1,981,000
Class A
Class of Stock [Line Items]
Number of shares of common stock issued (shares)		501	220	721
Common stock offering	$ 200,000	$ 5,007,000	$ 2,000,000	$ 7,007,000
Class T
Class of Stock [Line Items]
Number of shares of common stock issued (shares)		296		296
Common stock offering		$ 2,831,000		$ 2,831,000
Class I
Class of Stock [Line Items]
Number of shares of common stock issued (shares)		74	0	74
Common stock offering		$ 669,000	$ 0	$ 669,000