Segment Information - Reconciliation of Consolidated Net Income to Consolidated NOI (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting [Abstract]
Net income	$ 4,020	$ 8,087	$ 6,252	$ 4,583	$ 12,107	$ 10,835
Plus:
Interest expense	20,191		20,516		40,200	40,873
Interest expense - amortization of deferred financing costs	731		666		1,480	1,332
Depreciation and amortization	49,743		51,667		101,781	103,111
General and administrative expenses	8,343		8,399		16,904	18,243
Equity in loss of Real Estate Ventures	2,203		1,491		4,094	2,849
Less:
Interest income	445		553		1,020	1,078
Income tax (provision) benefit	230		(17)		226	(46)
Net gain on disposition of real estate	0		0		2,586	0
Net gain on sale of undepreciated real estate	201		250		201	1,251
Net gain on real estate venture transactions	0		1,276		0	1,535
Consolidated net operating income	$ 84,355		$ 86,929		$ 172,533	$ 173,425