Unconsolidated Entities - Summary of Operating Information and Financial Position of Unconsolidated Co-investment Ventures (Detail) - Unconsolidated Co-Investment Ventures [Member] ft² in Millions, $ in Millions		12 Months Ended
		Dec. 31, 2017 USD ($) ft² Property Venture	Dec. 31, 2016 USD ($) ft² Property Venture	Dec. 31, 2015 USD ($) ft² Property Venture
Schedule Of Equity Method Investments [Line Items]
Number of ventures | Venture		8	9	9
Number of buildings | Property		1,559	1,367	1,350
Square feet | ft²		332	291	277
Total assets		$ 28,899	$ 23,057	$ 22,553
Third-party debt		8,079	6,546	6,250
Total liabilities		9,642	7,876	7,593
Our investment balance	[1]	5,275	4,058	4,585
Revenues		2,180	1,943	1,832
Net earnings		$ 798	$ 562	$ 451
Weighted Average [Member]
Schedule Of Equity Method Investments [Line Items]
Ownership Percentage	[2]	28.80%	27.90%	31.60%
U.S. [Member]
Schedule Of Equity Method Investments [Line Items]
Number of ventures | Venture		1	1	1
Number of buildings | Property		552	369	391
Square feet | ft²		88	50	50
Total assets		$ 7,062	$ 4,238	$ 4,408
Third-party debt		2,313	1,414	1,433
Total liabilities		2,520	1,540	1,550
Our investment balance	[1]	1,383	435	690
Revenues		533	395	382
Net earnings		$ 139	$ 57	$ 35
U.S. [Member] | Weighted Average [Member]
Schedule Of Equity Method Investments [Line Items]
Ownership Percentage	[2]	28.20%	14.90%	22.50%
Other Americas [Member]
Schedule Of Equity Method Investments [Line Items]
Number of ventures | Venture		2	2	2
Number of buildings | Property		205	213	205
Square feet | ft²		37	42	39
Total assets		$ 2,118	$ 2,793	$ 2,482
Third-party debt		756	739	657
Total liabilities		782	814	708
Our investment balance	[1]	555	845	786
Revenues		245	242	228
Net earnings		$ 71	$ 71	$ 78
Other Americas [Member] | Weighted Average [Member]
Schedule Of Equity Method Investments [Line Items]
Ownership Percentage	[2]	43.40%	43.90%	43.80%
Europe [Member]
Schedule Of Equity Method Investments [Line Items]
Number of ventures | Venture		3	4	4
Number of buildings | Property		707	700	688
Square feet | ft²		166	163	159
Total assets		$ 13,586	$ 10,853	$ 11,343
Third-party debt		2,682	2,446	2,640
Total liabilities		3,655	3,283	3,584
Our investment balance	[1]	2,813	2,327	2,707
Revenues		1,030	964	947
Net earnings		$ 406	$ 333	$ 261
Europe [Member] | Weighted Average [Member]
Schedule Of Equity Method Investments [Line Items]
Ownership Percentage	[2]	32.80%	35.10%	38.90%
Asia [Member]
Schedule Of Equity Method Investments [Line Items]
Number of ventures | Venture		2	2	2
Number of buildings | Property		95	85	66
Square feet | ft²		41	36	29
Total assets		$ 6,133	$ 5,173	$ 4,320
Third-party debt		2,328	1,947	1,520
Total liabilities		2,685	2,239	1,751
Our investment balance	[1]	524	451	402
Revenues		372	342	275
Net earnings		$ 182	$ 101	$ 77
Asia [Member] | Weighted Average [Member]
Schedule Of Equity Method Investments [Line Items]
Ownership Percentage	[2]	15.10%	15.10%	15.00%

[1] The difference between our ownership interest of a venture’s equity and our investment balance at December 31, 2017, 2016 and 2015, results principally from three types of transactions: (i) deferring a portion of the gains we recognize from a contribution of a property to a venture ($667.3 million, $469.9 million and $430.7 million, respectively); (ii) recording additional costs associated with our investment in the venture ($94.2 million, $124.1 million and $122.1 million, respectively); and (iii) advances to a venture ($210.0 million, $166.1 million and $189.7 million, respectively).

[2] Represents our weighted average ownership interest in all co-investment ventures based on each entity’s contribution of total assets, before depreciation, net of other liabilities