CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Total	Total Stockholders’ Equity	Common Stock	Additional Paid-in Capital	Cumulative Distributions in Excess of Net Income (Loss)	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interest
Balance (in shares) at Dec. 31, 2017			180,864,707
Balance at Dec. 31, 2017	$ 1,079,408	$ 1,079,108	$ 1,809	$ 1,591,640	$ (514,451)	$ 110	$ 300
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	30,309	30,309			30,309
Other comprehensive loss	(110)	(110)				(110)
Issuance of common stock (in shares)			3,806,525
Issuance of common stock	42,443	42,443	$ 38	42,405
Transfers from redeemable common stock	8,813	8,813		8,813
Redemptions of common stock (in shares)			(8,248,444)
Redemptions of common stock	(94,569)	(94,569)	$ (83)	(94,486)
Distributions declared	(86,394)	(86,394)			(86,394)
Other offering costs	(2)	(2)		(2)
Balance (in shares) at Sep. 30, 2018			176,422,788
Balance at Sep. 30, 2018	979,898	979,598	$ 1,764	1,548,370	(570,536)	0	300
Balance (in shares) at Jun. 30, 2018			175,274,174
Balance at Jun. 30, 2018	1,012,898	1,012,598	$ 1,753	1,548,383	(537,623)	85	300
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(4,070)	(4,070)			(4,070)
Other comprehensive loss	(85)	(85)				(85)
Issuance of common stock (in shares)			1,250,379
Issuance of common stock	13,942	13,942	$ 13	13,929
Transfers to redeemable common stock	(12,744)	(12,744)		(12,744)
Redemptions of common stock (in shares)			(101,765)
Redemptions of common stock	(1,198)	(1,198)	$ (2)	(1,196)
Distributions declared	(28,843)	(28,843)			(28,843)
Other offering costs	(2)	(2)		(2)
Balance (in shares) at Sep. 30, 2018			176,422,788
Balance at Sep. 30, 2018	$ 979,898	979,598	$ 1,764	1,548,370	(570,536)	0	300
Balance (in shares) at Dec. 31, 2018	177,523,853		177,523,853
Balance at Dec. 31, 2018	$ 930,895	930,612	$ 1,775	1,555,380	(626,543)	0	283
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	262,067	262,091			262,091		(24)
Other comprehensive loss	0
Issuance of common stock (in shares)			3,434,259
Issuance of common stock	39,219	39,219	$ 34	39,185
Transfers from redeemable common stock	13,164	13,164		13,164
Redemptions of common stock (in shares)			(8,520,642)
Redemptions of common stock	(97,672)	(97,672)	$ (85)	(97,587)
Distributions declared	(85,285)	(85,285)			(85,285)
Other offering costs	$ (3)	(3)		(3)
Balance (in shares) at Sep. 30, 2019	172,437,470		172,437,470
Balance at Sep. 30, 2019	$ 1,062,385	1,062,126	$ 1,724	1,510,139	(449,737)	0	259
Balance (in shares) at Jun. 30, 2019			175,001,561
Balance at Jun. 30, 2019	814,104	813,838	$ 1,750	1,550,351	(738,263)	0	266
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	316,877	316,884			316,884		(7)
Other comprehensive loss	0
Issuance of common stock (in shares)			1,116,391
Issuance of common stock	12,748	12,748	$ 11	12,737
Transfers to redeemable common stock	(10,864)	(10,864)		(10,864)
Redemptions of common stock (in shares)			(3,680,482)
Redemptions of common stock	(42,122)	(42,122)	$ (37)	(42,085)
Distributions declared	$ (28,358)	(28,358)			(28,358)
Balance (in shares) at Sep. 30, 2019	172,437,470		172,437,470
Balance at Sep. 30, 2019	$ 1,062,385	$ 1,062,126	$ 1,724	$ 1,510,139	$ (449,737)	$ 0	$ 259