Variable Interest Entities - Consolidated Assets and Liabilities of VIEs (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018
ASSETS
Buildings and improvements	$ 11,784,671	$ 10,877,248
Development costs and construction in progress	496,662	537,643
Land	1,879,227	1,637,506
Accumulated depreciation and amortization	(2,926,656)	(2,842,947)
Net real estate	11,233,904	10,209,450
Investments in and advances to unconsolidated joint ventures	518,033	540,088
Accounts receivable, net	53,840	48,171
Cash and cash equivalents	130,521	110,790	$ 91,381
Restricted cash	25,531	29,056	$ 30,548
Intangible assets, net	317,960	305,079
Right-of-use asset, net	172,424
Other assets, net	618,218	591,017
Total assets	13,713,093	12,718,553
LIABILITIES AND EQUITY
Mortgage debt	161,829	138,470
Intangible liabilities, net	53,771	54,663
Lease liability	154,877
Accounts payable and accrued liabilities	30,093	1,125
Deferred revenue	193,286	190,683
Total liabilities	7,093,821	6,205,962
VIEs
ASSETS
Buildings and improvements	2,454,366	1,949,582
Development costs and construction in progress	49,101	39,584
Land	267,288	151,746
Accumulated depreciation and amortization	(416,738)	(398,143)
Net real estate	2,354,017	1,742,769
Investments in and advances to unconsolidated joint ventures	0	1,550
Accounts receivable, net	5,329	7,904
Cash and cash equivalents	55,574	23,772
Restricted cash	4,349	3,399
Intangible assets, net	137,749	111,333
Right-of-use asset, net	93,363	0
Other assets, net	43,610	43,149
Total assets	2,693,991	1,933,876
LIABILITIES AND EQUITY
Mortgage debt	98,064	44,598
Intangible liabilities, net	16,162	19,128
Lease liability	90,266	0
Accounts payable and accrued liabilities	57,310	66,736
Deferred revenue	24,119	24,215
Total liabilities	$ 285,921	$ 154,677