Real Estate - Investments in Real Estate Properties (Detail) ft² in Thousands, $ in Thousands	Jun. 30, 2018 USD ($) ft² a Buildings Property	Dec. 31, 2017 USD ($) ft² a Buildings
Real Estate Properties [Line Items]
Number of buildings | Property	3
Total investments in real estate properties	$ 25,555,343	$ 25,838,644
Less accumulated depreciation	4,283,877	4,059,348
Net investments in real estate properties	$ 21,271,466	$ 21,779,296
Improved Land [Member]
Real Estate Properties [Line Items]
Square Feet | ft²	0	0
Number of buildings | Buildings	0	0
Total investments in real estate properties	$ 5,608,507	$ 5,735,978
Building and Improvements [Member]
Real Estate Properties [Line Items]
Square Feet | ft²	287,393	294,811
Number of buildings | Buildings	1,477	1,525
Total investments in real estate properties	$ 16,658,627	$ 16,849,349
Development Portfolio, Including Cost of Land: Pre-stabilized [Member]
Real Estate Properties [Line Items]
Square Feet | ft²	6,024	7,345
Number of buildings | Buildings	20	22
Total investments in real estate properties	$ 471,491	$ 546,173
Properties Under Development [Member]
Real Estate Properties [Line Items]
Square Feet | ft²	21,317	22,216
Number of buildings | Buildings	63	63
Total investments in real estate properties	$ 1,184,404	$ 1,047,316
Land [Member]
Real Estate Properties [Line Items]
Square Feet | a	5,220	5,191
Total investments in real estate properties	$ 1,111,185	$ 1,154,383
Other Real Estate Investments [Member]
Real Estate Properties [Line Items]
Square Feet | ft²	0	0
Number of buildings | Buildings	0	0
Total investments in real estate properties	$ 521,129	$ 505,445