Investments in and Advances to Unconsolidated Affiliates (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Notes receivable, net	$ 276,163				$ 147,188				$ 276,163	$ 147,188
Combined and Condensed Balance Sheets
Real estate under development, at cost	543,486				609,574				543,486	609,574
Investments in and advances to unconsolidated affiliates	272,028				173,277				272,028	173,277
Other assets	192,786				123,789				192,786	123,789
Total assets	3,995,960				3,032,319				3,995,960	3,032,319
Total liabilities and equity	3,995,960				3,032,319				3,995,960	3,032,319
Investments in and advances to unconsolidated affiliates, net of Company's share of distributions in excess of income and investments in unconsolidated affiliates	258,337				160,033				258,337	160,033
Combined and Condensed Statements of Operations [Abstract]
Total revenues	54,121	$ 43,855	$ 43,918	$ 48,045	51,286	$ 51,124	$ 49,176	$ 49,073	189,939	199,063	$ 179,681
Operating and other expenses									(168,050)	(154,601)	(128,749)
Equity in earnings (losses) of unconsolidated affiliates									39,449	37,330	111,578
Depreciation and amortization									(70,011)	(60,751)	(49,645)
Income from continuing operations before gain on disposition of properties									52,627	60,907	137,786
Equity Method Investee [Member]
Schedule of Equity Method Investments [Line Items]
Related party revenue									1,200	300	200
Expenses, related party									1,100	800	2,800
Unconsolidated Affiliates [Member]
Combined and Condensed Balance Sheets
Rental property, net	576,505				302,976				576,505	302,976
Real estate under development, at cost	18,884				35,743				18,884	35,743
Investments in and advances to unconsolidated affiliates	6,853				6,853				6,853	6,853
Other assets	75,254				47,083				75,254	47,083
Total assets	677,496				392,655				677,496	392,655
Mortgage notes payable	407,344				262,130				407,344	262,130
Other liabilities	30,117				21,945				30,117	21,945
Partners’ equity	240,035				108,580				240,035	108,580
Total liabilities and equity	677,496				392,655				677,496	392,655
Company's share of accumulated equity	191,049				106,442				191,049	106,442
Basis differential	61,827				11,620				61,827	11,620
Deferred fees, net of portion related to the Company's interest	3,268				5,342				3,268	5,342
Amounts receivable by the Company	$ 2,193				36,629				2,193	36,629
Combined and Condensed Statements of Operations [Abstract]
Total revenues									84,218	43,990	44,422
Operating and other expenses									(25,724)	(13,721)	(17,069)
Interest expense									(16,300)	(9,178)	(9,363)
Equity in earnings (losses) of unconsolidated affiliates									0	66,655	(328)
Depreciation and amortization									(35,432)	(12,154)	(10,967)
Loss on debt extinguishment									0	0	(187)
(Loss) gain on disposition of properties									(1,340)	32,623	142,615
Income from continuing operations before gain on disposition of properties									5,422	108,215	149,123
Operating Partnership, as General Partner or Managing Member [Member]
Combined and Condensed Statements of Operations [Abstract]
Equity in earnings (losses) of unconsolidated affiliates									39,449	37,330	111,578
Company’s share of equity in net income of unconsolidated affiliates									40,538	37,722	111,970
Basis differential adjustments									$ (1,089)	(392)	$ (392)
Broughton Street Portfolio [Member]
Schedule of Equity Method Investments [Line Items]
Notes receivable, net					$ 35,900					35,900
Mervyns I and Mervyns II [Member] | Unconsolidated Affiliates [Member]
Combined and Condensed Statements of Operations [Abstract]
Equity in earnings (losses) of unconsolidated affiliates										$ 5,900