Variable Interest Entities - Consolidated Assets and Liabilities of VIEs (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
ASSETS
Buildings and improvements	$ 11,829,835	$ 10,877,248
Development costs and construction in progress	603,672	537,643
Land	2,017,284	1,637,506
Accumulated depreciation and amortization	(2,915,680)	(2,842,947)
Net real estate	11,535,111	10,209,450
Investments in and advances to unconsolidated joint ventures	505,245	540,088
Accounts receivable, net	56,991	48,171
Cash and cash equivalents	124,990	110,790	$ 78,864
Restricted cash	30,114	29,056	$ 29,877
Intangible assets, net	303,722	305,079
Right-of-use asset, net	172,958
Other assets, net	656,115	591,017
Total assets	14,010,210	12,718,553
LIABILITIES AND EQUITY
Mortgage debt	275,049	138,470
Intangible liabilities, net	54,913	54,663
Lease liability	156,297
Accounts payable and accrued liabilities	35,063	1,125
Deferred revenue	208,653	190,683
Total liabilities	7,486,851	6,205,962
VIEs
ASSETS
Buildings and improvements	2,799,041	1,949,582
Development costs and construction in progress	54,154	39,584
Land	426,027	151,746
Accumulated depreciation and amortization	(474,996)	(398,143)
Net real estate	2,804,226	1,742,769
Investments in and advances to unconsolidated joint ventures	0	1,550
Accounts receivable, net	6,151	7,904
Cash and cash equivalents	53,745	23,772
Restricted cash	8,976	3,399
Intangible assets, net	146,319	111,333
Right-of-use asset, net	92,933	0
Other assets, net	47,597	43,149
Total assets	3,159,947	1,933,876
LIABILITIES AND EQUITY
Mortgage debt	216,340	44,598
Intangible liabilities, net	18,212	19,128
Lease liability	90,487	0
Accounts payable and accrued liabilities	78,815	66,736
Deferred revenue	28,084	24,215
Total liabilities	$ 431,938	$ 154,677