Investments in and Advances to Unconsolidated Affiliates - Unconsolidated Affiliates - Schedule of Condensed Income Statement (Details) - USD ($) $ 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
Combined and Condensed Statements of Income
Revenues	$ 77,786	$ 73,327	$ 70,229	$ 73,985	$ 69,727	$ 65,527	$ 62,201	$ 62,226	$ 295,327	$ 259,681	$ 248,552
Operating and other expenses									(253,048)	(232,140)	(231,233)
Depreciation and amortization									(125,443)	(117,549)	(104,934)
Company’s share of equity in net income of unconsolidated affiliates									11,772	12,345	26,039
Company’s equity in earnings of unconsolidated affiliates									8,922	9,302	23,371
Unconsolidated Affiliates
Combined and Condensed Statements of Income
Revenues									88,585	80,184	83,222
Operating and other expenses									(24,624)	(23,586)	(24,711)
Interest expense									(21,874)	(19,954)	(18,733)
Depreciation and amortization									(25,358)	(22,228)	(24,192)
Loss on debt extinguishment											(154)
(Loss) gain on disposition of properties										(1,673)	18,957
Net income attributable to unconsolidated affiliates									16,729	12,743	34,389
Operating Partnership, as General Partner or Managing Member
Combined and Condensed Statements of Income
Basis differential amortization									$ (2,850)	$ (3,043)	$ (2,668)