Variable Interest Entities - Narrative (Details)	9 Months Ended
	Sep. 30, 2023 USD ($) loan collateralized_loan_obligation	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)	Sep. 30, 2022 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
Variable interest entities
Number of CLOs | collateralized_loan_obligation	5
Number of SASBs | loan	1
VIE assets	$ 70,293,689,000		$ 79,043,129,000
VIE liabilities	63,200,233,000		71,844,422,000
Temporary equity	409,659,000	$ 408,034,000	362,790,000	$ 344,373,000	$ 322,753,000	$ 214,915,000
Investments in unconsolidated entities	$ 91,924,000		$ 91,892,000
CMBS JV
Variable interest entities
Ownership percentage	51.00%
Primary Beneficiary
Variable interest entities
VIE assets	$ 74,800,000
VIE liabilities	34,800,000
Primary Beneficiary | CMBS Venture Holdings
Variable interest entities
VIE assets	341,300,000
VIE liabilities	83,900,000
Primary Beneficiary | SPT Dolphin
Variable interest entities
VIE assets	2,000,000,000
VIE liabilities	0
Primary Beneficiary | Woodstar Feeder Fund, L.P.
Variable interest entities
VIE assets	600,000,000
VIE liabilities	0
Temporary equity	400,000,000
Not primary beneficiary
Variable interest entities
Maximum risk of loss related to VIEs, on fair value basis	18,700,000
Not primary beneficiary | Measurement Period Adjustments
Variable interest entities
Investments in unconsolidated entities	900,000
Not primary beneficiary | Securitization SPEs
Variable interest entities
Long term debt, gross	$ 4,500,000,000