Loans and Allowance for Credit Losses - Activity in the Allowance for Credit Losses for Loans Held for Investment (Details) - USD ($)	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 174,000,000
Provision	12,000,000	$ 27,000,000
Charge-offs	(9,000,000)
Ending balance	176,000,000
Held-to-Maturity Securities
Beginning balance	0	1,000,000
Provision	0	0
Charge-offs		0
Ending balance	0	1,000,000
Leveraged Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	68,000,000	72,000,000
Provision	6,000,000	5,000,000
Charge-offs	(9,000,000)	(6,000,000)
Ending balance	65,000,000	71,000,000
Other Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	4,000,000	4,000,000
Provision	2,000,000	1,000,000
Charge-offs	0	0
Ending balance	6,000,000	5,000,000
Other Loans | Fund Finance
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Ending balance	4,000,000	4,000,000
Other Loans | Other Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Ending balance	2,000,000	1,000,000
Commercial Real Estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	102,000,000	60,000,000
Provision	3,000,000	25,000,000
Charge-offs	0	(25,000,000)
Ending balance	105,000,000	60,000,000
Off-Balance Sheet Commitments
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	9,000,000	14,000,000
Provision	1,000,000	(4,000,000)
Charge-offs	0	0
Ending balance	10,000,000	10,000,000
All Other
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		(1,000,000)
Provision		0
Charge-offs		0
Ending balance		(1,000,000)
Total
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	183,000,000	150,000,000
Provision	12,000,000	27,000,000
Charge-offs	(9,000,000)	(31,000,000)
Ending balance	$ 186,000,000	$ 146,000,000