Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Oct. 31, 2021	Dec. 31, 2020
Securities Financing Transaction [Line Items]
Accrued performance allocations and incentive fee related compensation	$ 4,057.2		$ 4,057.2			$ 2,534.4
Securities transferred to counterparties under repurchase agreements	148.8		148.8
Foreign currency transaction gain (loss)	$ (9.9)	$ (2.6)	$ (11.8)	$ 18.9
Subsequent event
Securities Financing Transaction [Line Items]
Realized performance allocation related compensation percentage (percent)					20.00%