Loans and Allowance for Credit Losses - Activity in the Allowance for Credit Losses for Loans Held for Investment (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance			$ 135,000,000
Provision for credit losses	$ 26,000,000	$ 0	63,000,000	$ 26,000,000
Ending balance	162,000,000		162,000,000
Available-for-sale Securities
Beginning balance		0	0	2,000,000
Charge-offs	0	0		0
Provision		0		(2,000,000)
Ending balance	0	0	0	0
Held-to-Maturity Securities
Beginning balance	1,000,000	0	1,000,000	0
Charge-offs	0	0	0	0
Provision	0	1,000,000	0	1,000,000
Ending balance	1,000,000	1,000,000	1,000,000	1,000,000
Leveraged Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	56,000,000	80,000,000	72,000,000	73,000,000
Charge-offs		(2,000,000)	(17,000,000)	(13,000,000)
Provision for credit losses	12,000,000	(6,000,000)	13,000,000	12,000,000
Ending balance	68,000,000	72,000,000	68,000,000	72,000,000
Other Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	4,000,000	3,000,000	3,000,000	5,000,000
Charge-offs		0	0	0
Provision for credit losses	0	0	1,000,000	(2,000,000)
Ending balance	4,000,000	3,000,000	4,000,000	3,000,000
Other Loans | Fund Finance
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Ending balance	3,000,000	2,000,000	3,000,000	2,000,000
Other Loans | Other Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Ending balance	1,000,000	1,000,000	1,000,000	1,000,000
Commercial Real Estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	76,000,000	37,000,000	60,000,000	19,000,000
Charge-offs		0	(25,000,000)	0
Provision for credit losses	14,000,000	7,000,000	55,000,000	25,000,000
Ending balance	90,000,000	44,000,000	90,000,000	44,000,000
Off-Balance Sheet Commitments
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	8,000,000	15,000,000	14,000,000	23,000,000
Charge-offs		0	0	0
Provision for credit losses	0	(1,000,000)	(6,000,000)	(9,000,000)
Ending balance	8,000,000	14,000,000	8,000,000	14,000,000
All Other
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		1,000,000		(1,000,000)
Charge-offs		0		0
Provision for credit losses		(1,000,000)		1,000,000
Ending balance		0		0
Total
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	145,000,000	136,000,000	150,000,000	121,000,000
Charge-offs		(2,000,000)	(42,000,000)	(13,000,000)
Provision for credit losses	26,000,000	0	63,000,000	26,000,000
Ending balance	$ 171,000,000	$ 134,000,000	$ 171,000,000	$ 134,000,000