Investments in and Advances to Unconsolidated Affiliates - Unconsolidated Affiliates (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Combined and Condensed Balance Sheets
Real estate under development	$ 173,702				$ 543,486				$ 173,702	$ 543,486
Investments in and advances to unconsolidated affiliates	302,070				272,028				302,070	272,028
Other assets	214,959				192,786				214,959	192,786
Total assets	3,960,247				3,995,960				3,960,247	3,995,960
Total liabilities and equity	3,960,247				3,995,960				3,960,247	3,995,960
Investments in and advances to unconsolidated affiliates, net of Company's share of distributions in excess of income from and investments in unconsolidated affiliates	286,778				258,337				286,778	258,337
Combined and Condensed Statements of Income
Total revenues	66,081	$ 62,678	$ 59,504	$ 61,999	54,121	$ 43,855	$ 43,918	$ 48,045	250,262	189,939	$ 199,063
Operating and other expenses									(232,943)	(168,050)	(154,601)
Depreciation and amortization									(104,934)	(70,011)	(60,751)
Income from continuing operations before gain on disposition of properties									15,422	52,627	60,907
Company’s equity in earnings of unconsolidated affiliates									23,371	39,449	37,330
Equity Method Investee
Schedule of Equity Method Investments [Line Items]
Related party revenue									1,300	1,200	300
Expenses, related party									2,000	2,400	2,500
Unconsolidated Affiliates
Combined and Condensed Balance Sheets
Rental property, net	518,900				576,505				518,900	576,505
Real estate under development	26,681				18,884				26,681	18,884
Investments in and advances to unconsolidated affiliates	6,853				6,853				6,853	6,853
Other assets	100,901				75,254				100,901	75,254
Total assets	653,335				677,496				653,335	677,496
Mortgage notes payable	405,652				407,344				405,652	407,344
Other liabilities	61,932				30,117				61,932	30,117
Partners’ equity	185,751				240,035				185,751	240,035
Total liabilities and equity	653,335				677,496				653,335	677,496
Company's share of accumulated equity	185,533				191,049				185,533	191,049
Basis differential	95,358				61,827				95,358	61,827
Deferred fees, net of portion related to the Company's interest	3,472				3,268				3,472	3,268
Amounts receivable by the Company	$ 2,415				$ 2,193				2,415	2,193
Combined and Condensed Statements of Income
Total revenues									83,222	84,218	43,990
Operating and other expenses									(24,711)	(25,724)	(13,721)
Interest expense									(18,733)	(16,300)	(9,178)
Depreciation and amortization									(24,192)	(35,432)	(12,154)
Loss on debt extinguishment									(154)	0	0
Gain (loss) on disposition of properties									18,957	(1,340)	32,623
Income from continuing operations before gain on disposition of properties									34,389	5,422	108,215
Company’s equity in earnings of unconsolidated affiliates									0	0	66,655
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									26,039	40,538	37,722
Basis differential amortization									(2,668)	(1,089)	(392)
Company’s equity in earnings of unconsolidated affiliates									$ 23,371	$ 39,449	$ 37,330