Real Estate - Investments in Real Estate Properties (Detail) ft² in Thousands, $ in Thousands	Dec. 31, 2016 USD ($) ft² a Buildings	Dec. 31, 2015 USD ($) ft² a Buildings
Real Estate Properties [Line Items]
Total investments in real estate properties	$ 27,119,330	$ 27,521,368
Less accumulated depreciation	3,758,372	3,274,284
Net investments in real estate properties	$ 23,360,958	$ 24,247,084
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	$ 6,037,543	$ 5,874,052
Building and Improvements [Member]
Real Estate Properties [Line Items]
Square Feet | ft²	331,210	333,830
Number of buildings | Buildings	1,776	1,872
Total investments in real estate properties	$ 17,905,914	$ 17,861,693
Development Portfolio, Including Cost of Land: Pre-stabilized [Member]
Real Estate Properties [Line Items]
Square Feet | ft²	8,256	12,598
Number of buildings | Buildings	29	28
Total investments in real estate properties	$ 798,233	$ 918,099
Properties Under Development [Member]
Real Estate Properties [Line Items]
Square Feet | ft²	19,539	19,630
Number of buildings | Buildings	60	63
Total investments in real estate properties	$ 633,849	$ 954,804
Land [Member]
Real Estate Properties [Line Items]
Square Feet | a	5,892	7,404
Total investments in real estate properties	$ 1,218,904	$ 1,359,794
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	$ 524,887	$ 552,926