Variable Interest Entities - Consolidated Assets and Liabilities of VIEs (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
ASSETS
Buildings and improvements	$ 11,114,139	$ 11,692,654
Development costs and construction in progress	444,528	400,619
Land	1,765,305	1,881,487
Accumulated Depreciation	(2,672,489)	(2,648,930)
Net real estate	10,651,483	11,325,830
Investments in and advances to unconsolidated joint ventures	829,231	571,491
Accounts Receivable, Net	36,969	45,116
Cash and cash equivalents	391,965	94,730
Restricted cash	61,481	42,260
Intangible assets, net	414,404	479,805
Other assets, net	611,690	711,624
Total assets	14,102,575	15,759,265
LIABILITIES AND EQUITY
Mortgage debt	146,337	623,792
Intangible liabilities, net	51,463	58,145
Liabilities of assets held for sale, net	0	3,776
Deferred revenue	147,155	149,181
Total liabilities	8,073,634	9,817,957
VIEs
ASSETS
Buildings and improvements	2,796,279	3,522,310
Development costs and construction in progress	17,702	31,953
Land	222,893	327,241
Accumulated Depreciation	(559,789)	(676,276)
Net real estate	2,477,085	3,205,228
Investments in and advances to unconsolidated joint ventures	2,573	3,641
Accounts Receivable, Net	12,062	19,996
Cash and cash equivalents	45,034	35,844
Restricted cash	41,843	22,624
Intangible assets, net	133,210	169,027
Other assets, net	53,400	69,562
Total assets	2,765,207	3,525,922
LIABILITIES AND EQUITY
Mortgage debt	45,156	520,870
Intangible liabilities, net	8,475	8,994
Liabilities of assets held for sale, net	100,648	120,719
Deferred revenue	18,453	23,456
Total liabilities	$ 172,732	$ 674,039