Assets Held for Sale or Contribution - Summary of Assets Held for Sale or Contribution (Detail) ft² in Thousands, $ in Thousands	Sep. 30, 2021 USD ($) ft² Property	Dec. 31, 2020 USD ($) ft² Property	[1]
Long Lived Assets Held For Sale [Line Items]
Total assets held for sale or contribution	$ 571,671	$ 1,070,724
Total liabilities associated with assets held for sale or contribution – included in Other Liabilities	$ 6,178	$ 16,214
Disposal Group Held for Sale Not Discontinued Operations [Member]
Long Lived Assets Held For Sale [Line Items]
Number of operating properties | Property	17	66
Square feet | ft²	5,856	12,923

[1] At December 31, 2020, Assets Held for Sale or Contribution included certain properties acquired through the Liberty Transaction and the IPT Transaction that were subsequently sold during 2021.