Commitments and Contingencies - Schedule of Principal Debt Repayments (Parenthetical) (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)
Debt Instrument [Line Items]
Non-consolidated senior interests excluded from contractual obligations	$ 801.8
Securitized debt obligations excluded from contractual obligations	$ 2,900.0
Debt Instrument Amortization Percentage	1.00%
Nonconsolidated securitized debt excluded from contractual obligations	$ 656.3