Debt - Debt Summary (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Debt	$ 10,608,294	$ 11,626,831
Credit Facilities [Member]
Debt Instrument [Line Items]
Debt	35,023	0
Senior Notes [Member]
Debt Instrument [Line Items]
Debt	6,417,492	$ 6,516,392
Term Loan [Member]
Debt Instrument [Line Items]
Debt	$ 1,500,000
Debts Of Operating Partnership [Member]
Debt Instrument [Line Items]
Weighted Average Interest Rate	3.20%	3.20%
Debt	$ 10,608,294	$ 11,626,831
Debts Of Operating Partnership [Member] | Credit Facilities [Member]
Debt Instrument [Line Items]
Weighted Average Interest Rate	1.00%	0.00%
Debt	$ 35,023	$ 0
Debts Of Operating Partnership [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Weighted Average Interest Rate	3.30%	3.30%
Debt	$ 6,417,492	$ 6,516,392
Debts Of Operating Partnership [Member] | Term Loan [Member]
Debt Instrument [Line Items]
Weighted Average Interest Rate	1.40%	2.10%
Debt	$ 1,484,523	$ 2,100,009
Debts Of Operating Partnership [Member] | Unsecured Other Debt [Member]
Debt Instrument [Line Items]
Weighted Average Interest Rate	6.10%	6.20%
Debt	$ 14,478	$ 15,448
Debts Of Operating Partnership [Member] | Secured Mortgages [Member]
Debt Instrument [Line Items]
Weighted Average Interest Rate	4.90%	5.10%
Debt	$ 979,585	$ 1,172,473
Debts Of Operating Partnership [Member] | Secured Mortgage Debt of Consolidated Entities [Member]
Debt Instrument [Line Items]
Weighted Average Interest Rate	3.00%	2.90%
Debt	$ 1,677,193	$ 1,822,509