Condensed Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Cumulative Distributions in Excess of Earnings
Beginning balance at Dec. 31, 2015	$ 262,288	$ 477	$ 410,217	$ (148,406)
Beginning balance (in shares) at Dec. 31, 2015		47,664,742
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, net	200,398	$ 170	200,228
Issuance of common stock, net, (in shares)		17,023,824
Vesting of restricted common stock, net of shares withheld for employee taxes	(515)	$ 1	(516)
Vesting of restricted common stock, net of shares withheld for employee taxes (in shares)		127,784
Amortization of stock-based compensation	1,546		1,546
Common dividends ($0.555 and $0.68 per share for the nine months ended 9/30/2017 and year ended 12/31/2016, respectively) (in usd per share)	(40,640)			(40,640)
Net income	29,353			29,353
Ending balance at Dec. 31, 2016	452,430	$ 648	611,475	(159,693)
Ending balance (in shares) at Dec. 31, 2016		64,816,350
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, net	170,414	$ 106	170,308
Issuance of common stock, net, (in shares)		10,573,089
Vesting of restricted common stock, net of shares withheld for employee taxes	(867)	$ 1	(868)
Vesting of restricted common stock, net of shares withheld for employee taxes (in shares)		83,243
Amortization of stock-based compensation	1,792		1,792
Common dividends ($0.555 and $0.68 per share for the nine months ended 9/30/2017 and year ended 12/31/2016, respectively) (in usd per share)	(41,515)			(41,515)
Net income	23,622			23,622
Ending balance at Sep. 30, 2017	$ 605,876	$ 755	$ 782,707	$ (177,586)
Ending balance (in shares) at Sep. 30, 2017		75,472,682