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, 2016	$ 452,430	$ 648	$ 611,475	$ (159,693)
Beginning balance (in shares) at Dec. 31, 2016		64,816,350
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, net	170,319	$ 106	170,213
Issuance of common stock, net, (in shares)		10,573,089
Vesting of restricted common stock, net of shares withheld for employee taxes	(866)	$ 1	(867)
Vesting of restricted common stock, net of shares withheld for employee taxes (in shares)		88,763
Amortization of stock-based compensation	2,416		2,416
Common dividends ($0.41 and $0.74 per share for the six months ended 6/30/2018 and year ended 12/31/2017, respectively) (in usd per share)	(55,556)			(55,556)
Net income	25,874			25,874
Ending balance at Dec. 31, 2017	594,617	$ 755	783,237	(189,375)
Ending balance (in shares) at Dec. 31, 2017		75,478,202
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, net	47,540	$ 30	47,510
Issuance of common stock, net, (in shares)		2,988,813
Vesting of restricted common stock, net of shares withheld for employee taxes	(1,289)		(1,289)
Vesting of restricted common stock, net of shares withheld for employee taxes (in shares)		83,672
Amortization of stock-based compensation	1,828		1,828
Common dividends ($0.41 and $0.74 per share for the six months ended 6/30/2018 and year ended 12/31/2017, respectively) (in usd per share)	(31,832)			(31,832)
Net income	27,874			27,874
Ending balance at Jun. 30, 2018	$ 638,738	$ 785	$ 831,286	$ (193,333)
Ending balance (in shares) at Jun. 30, 2018		78,550,687