Summary of Significant Accounting Policies - Schedule of Gain on Sale of Real Estate (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Dispositions to third parties
Gross proceeds	$ 46.9	$ 60.4
Gain on sale of real estate, net	$ 24.2	$ 20.8

Amount of difference between the carrying amount and the sales price of real estate properties sold as part of discontinued operations.

No definition available.

Name:	us-gaap_GainLossOnDispositionOfRealEstateDiscontinuedOperations
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration