Real Estate - Summary of Dispositions (Detail) ft² in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017 USD ($) ft² Property	Jun. 30, 2016 USD ($) ft² Property	Jun. 30, 2017 USD ($) ft² Property	Jun. 30, 2016 USD ($) ft² Property
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total gains on dispositions of investments in real estate, net	$ 83,006	$ 200,350	$ 180,331	$ 344,667
Continuing Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total gains on contributions and dispositions, net	83,006	113,735	180,331	258,052
Total gains on dispositions of investments in real estate, net	$ 83,006	$ 200,350	$ 180,331	$ 344,667
Continuing Operations [Member] | Contributions to unconsolidated co-investment ventures [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of buildings | Property	5	5	10	10
Square feet | ft²	875	1,308	3,644	4,019
Net proceeds	$ 115,617	$ 65,805	$ 513,106	$ 463,700
Gains on contributions, net (1)	$ 37,702	$ 10,451	$ 126,068	$ 103,590
Continuing Operations [Member] | Dispositions to Third Parties [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of buildings | Property	20	72	38	99
Square feet | ft²	3,720	8,321	6,038	10,565
Net proceeds	$ 216,290	$ 609,028	$ 459,679	$ 889,607
Gains on contributions, net (1)	45,304	103,284	54,263	154,462
Continuing Operations [Member] | Redemption of investment in co-investment venture [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gains on contributions, net (1)	$ 0	$ 86,615	$ 0	$ 86,615