Quarterly Results (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 94,469	$ 95,440	$ 96,287	$ 88,718	$ 91,820	$ 90,191	$ 90,957	$ 89,438	$ 374,914	$ 362,406	$ 311,173
Net loss attributable to stockholders	$ (48,133)	$ (28,789)	$ (6,054)	$ (5,111)	$ (10,241)	$ (29,607)	$ (6,950)	$ (5,991)	$ (88,087)	$ (52,762)	$ (42,548)
Basic and diluted weighted average shares outstanding (in shares)	92,091,377	91,922,963	91,783,557	92,894,608	91,520,444	90,203,311	90,978,411	90,783,065	91,936,641	91,118,929	89,802,174
Basic and diluted net loss per share (in usd per share)	$ (0.52)	$ (0.31)	$ (0.07)	$ (0.06)	$ (0.11)	$ (0.33)	$ (0.08)	$ (0.07)	$ (0.96)	$ (0.58)	$ (0.47)
Business Acquisition [Line Items]
Impairment charges									$ 55,969	$ 20,655	$ 18,993
Held-for-use
Business Acquisition [Line Items]
Impairment charges									$ 33,335	$ 2,400	$ 18,993