Real Estate - Summary of Dispositions (Detail) ft² in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) ft² Property	Mar. 31, 2018 USD ($) ft² Property
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Square feet | ft²	967	0
Total gains on real estate transactions, net	$ 188,208	$ 195,111
Partial redemptions of investments in co-investment ventures [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gains on contributions, dispositions, or redemptions, net	135,022	0
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	$ 53,186	$ 195,111
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	19	8
Square feet | ft²	8,149	3,078
Net proceeds	$ 744,165	$ 539,822
Gains on contributions, dispositions, or redemptions, net	$ 37,138	$ 167,726
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	2	11
Square feet | ft²	670	1,303
Net proceeds	$ 52,024	$ 87,981
Gains on contributions, dispositions, or redemptions, net	$ 16,048	$ 27,385