Debt - Long-Term Debt Maturities (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
2016	$ 934,000
2017	1,087,000
2018	746,000
2019	1,067,000
2020	1,108,000
2021	1,744,000
2022	1,313,000
2023	1,293,000
2024	896,000
2025	881,000
Thereafter	552,000
Subtotal	11,621,000
Unamortized premiums (discounts), net	58,000
Unamortized debt issuance costs, net	(52,300)	$ (43,200)
Totals	11,626,831	9,336,977
Credit Facilities [Member]
Debt Instrument [Line Items]
Totals	0	0
Senior Notes [Member]
Debt Instrument [Line Items]
Totals	6,516,392	6,046,965
Secured Mortgage Debt [Member]
Debt Instrument [Line Items]
Totals	1,172,473	$ 1,042,628
Wholly Owned
Debt Instrument [Line Items]
2016	764,000
2017	571,000
2018	343,000
2019	924,000
2020	856,000
2021	1,616,000
2022	1,312,000
2023	1,151,000
2024	895,000
2025	880,000
Thereafter	550,000
Subtotal	9,862,000
Unamortized premiums (discounts), net	(10,000)
Unamortized debt issuance costs, net	(48,000)
Totals	9,804,000
Wholly Owned | Credit Facilities [Member]
Debt Instrument [Line Items]
2016	0
2017	0
2018	0
2019	0
2020	0
2021	0
2022	0
2023	0
2024	0
2025	0
Thereafter	0
Subtotal	0
Unamortized premiums (discounts), net	0
Unamortized debt issuance costs, net	0
Totals	0
Wholly Owned | Senior Notes [Member]
Debt Instrument [Line Items]
2016	0
2017	0
2018	175,000
2019	618,000
2020	849,000
2021	1,262,000
2022	762,000
2023	850,000
2024	762,000
2025	750,000
Thereafter	544,000
Subtotal	6,572,000
Unamortized premiums (discounts), net	(23,000)
Unamortized debt issuance costs, net	(33,000)
Totals	6,516,000
Wholly Owned | Term Loans And Other Debt
Debt Instrument [Line Items]
2016	401,000
2017	563,000
2018	1,000
2019	1,000
2020	1,000
2021	341,000
2022	541,000
2023	269,000
2024	1,000
2025	1,000
Thereafter	6,000
Subtotal	2,126,000
Unamortized premiums (discounts), net	0
Unamortized debt issuance costs, net	(10,000)
Totals	2,116,000
Wholly Owned | Secured Mortgage Debt [Member]
Debt Instrument [Line Items]
2016	363,000
2017	8,000
2018	167,000
2019	305,000
2020	6,000
2021	13,000
2022	9,000
2023	32,000
2024	132,000
2025	129,000
Thereafter	0
Subtotal	1,164,000
Unamortized premiums (discounts), net	13,000
Unamortized debt issuance costs, net	(5,000)
Totals	1,172,000
Consolidated Entities
Debt Instrument [Line Items]
2016	170,000
2017	516,000
2018	403,000
2019	143,000
2020	252,000
2021	128,000
2022	1,000
2023	142,000
2024	1,000
2025	1,000
Thereafter	2,000
Subtotal	1,759,000
Unamortized premiums (discounts), net	68,000
Unamortized debt issuance costs, net	(4,000)
Totals	$ 1,823,000