Investments in and Advances to Unconsolidated Affiliates - Unconsolidated Affiliates (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Combined and Condensed Balance Sheets
Real estate under development	$ 182,380		$ 173,702
Investments in and advances to unconsolidated affiliates	311,540		302,070
Other assets	216,514		214,959
Total assets	3,938,976		3,960,247
Total liabilities and equity	3,938,976		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	296,314		286,778
Company's share of distributions in excess of income from and investments in unconsolidated affiliates	15,226		15,292
Investments in and advances to unconsolidated affiliates	311,540		302,070
Combined and Condensed Statements of Income
Total revenues	63,124	$ 61,999
Operating and other expenses	(56,423)	(52,102)
Depreciation and amortization	(28,576)	(24,536)
Company’s equity in earnings of unconsolidated affiliates	1,684	12,703
Equity Method Investee
Schedule of Equity Method Investments [Line Items]
Related party revenue	300	400
Expenses, related party	500	500
Unconsolidated Affiliates
Combined and Condensed Balance Sheets
Rental property, net	509,634		518,900
Real estate under development	24,976		26,681
Investments in and advances to unconsolidated affiliates	6,853		6,853
Other assets	95,934		100,901
Total assets	637,397		653,335
Mortgage notes payable	405,955		405,652
Other liabilities	60,950		61,932
Partners’ equity	170,492		185,751
Total liabilities and equity	637,397		653,335
Company's share of accumulated equity	183,602		185,533
Basis differential	107,347		95,358
Deferred fees, net of portion related to the Company's interest	3,111		3,472
Amounts receivable by the Company	2,254		2,415
Investments in and advances to unconsolidated affiliates	6,853		$ 6,853
Combined and Condensed Statements of Income
Total revenues	20,156	21,603
Operating and other expenses	(5,921)	(5,866)
Interest expense	(4,874)	(4,538)
Depreciation and amortization	(6,055)	(6,449)
Loss on debt extinguishment	0	(151)
(Loss) gain on disposition of properties	(418)	14,446
Net income attributable to unconsolidated affiliates	2,888	19,045
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	2,267	13,569
Basis differential amortization	(583)	(866)
Company’s equity in earnings of unconsolidated affiliates	$ 1,684	$ 12,703