Investments in and Advances to Unconsolidated Affiliates - Unconsolidated Affiliates (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Combined and Condensed Balance Sheets
Real estate under development	$ 192,215		$ 192,215		$ 173,702
Investments in and advances to unconsolidated affiliates	306,616		306,616		302,070
Other assets	207,583		207,583		214,959
Total assets	3,880,768		3,880,768		3,960,247
Total liabilities and equity	3,880,768		3,880,768		3,960,247
Investments in and advances to unconsolidated affiliates, net of Company's share of distributions in excess of income from and investments in unconsolidated affiliates	291,408		291,408		286,778
Company's share of distributions in excess of income from and investments in unconsolidated affiliates	15,208		15,208		15,292
Investments in and advances to unconsolidated affiliates	306,616		306,616		302,070
Combined and Condensed Statements of Income
Revenues	63,569	$ 59,504	126,693	$ 121,503
Operating and other expenses	(57,270)	(52,762)	(113,693)	(104,864)
Depreciation and amortization	(29,503)	(26,057)	(58,079)	(50,593)
(Loss) income from continuing operations before gain on disposition of properties	(2,303)	6,108	(6,463)	26,079
Company’s equity in earnings of unconsolidated affiliates	5,019	4,340	6,703	17,043
Equity Method Investee
Schedule of Equity Method Investments [Line Items]
Related party revenue	300	300	500	600
Expenses, related party	400	400	900	1,000
Unconsolidated Affiliates
Combined and Condensed Balance Sheets
Rental property, net	527,330		527,330		518,900
Real estate under development	2,796		2,796		26,681
Investments in and advances to unconsolidated affiliates	6,853		6,853		6,853
Other assets	92,350		92,350		100,901
Total assets	629,329		629,329		653,335
Mortgage notes payable	406,579		406,579		405,652
Other liabilities	56,865		56,865		61,932
Partners’ equity	165,885		165,885		185,751
Total liabilities and equity	629,329		629,329		653,335
Company's share of accumulated equity	183,007		183,007		185,533
Basis differential	106,480		106,480		95,358
Deferred fees, net of portion related to the Company's interest	1,808		1,808		3,472
Amounts receivable by the Company	113		113		2,415
Investments in and advances to unconsolidated affiliates	6,853		6,853		$ 6,853
Combined and Condensed Statements of Income
Revenues	19,603	20,974	39,759	42,577
Operating and other expenses	(5,531)	(6,272)	(11,453)	(12,138)
Interest expense	(5,250)	(4,641)	(10,125)	(9,179)
Depreciation and amortization	(5,801)	(6,063)	(11,856)	(12,512)
Loss on debt extinguishment	0	(3)	0	(154)
(Loss) gain on disposition of properties	(992)	3,332	(1,410)	17,778
(Loss) income from continuing operations before gain on disposition of properties	2,029	7,327	4,915	26,372
Operating Partnership, as General Partner or Managing Member
Combined and Condensed Statements of Income
Company’s share of equity in net income of unconsolidated affiliates	5,895	5,044	8,260	18,612
Basis differential amortization	(876)	(704)	(1,557)	(1,569)
Company’s equity in earnings of unconsolidated affiliates	$ 5,019	$ 4,340	$ 6,703	$ 17,043