Real Estate - Additional Information (Detail) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Real Estate [Abstract]
Operating lease right-of-use assets	$ 425.6	$ 492.8
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Other assets	Other assets
Lease liabilities	$ 419.2	$ 487.0
Operating Lease, Liability, Statement of Financial Position [Extensible List]	Other liabilities	Other liabilities