Other Borrowings - Outstanding Credit Linked Noted Issuances (Details) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2025 USD ($) class	Dec. 31, 2024 USD ($)
Debt [Line Items]
Classes of notes \| class	6
Credit Linked Notes
Debt [Line Items]
Principal	$ 422	$ 434
Debt Issuance Costs	$ 7	$ 7
Minimum
Debt [Line Items]
Period of basis point spread	0.10%
Maximum
Debt [Line Items]
Period of basis point spread	0.20%
Credit Linked Notes Maturing October 2052 \| Credit Linked Notes
Debt [Line Items]
Period of basis point spread	7.80%	7.80%
Principal	$ 83	$ 84
Debt Issuance Costs	$ 2	2
Weighted average borrowing rate	7.80%
Reference pool balance	$ 1,600	$ 1,700
Credit Linked Notes Maturing October 2052 \| Minimum \| Credit Linked Notes
Debt [Line Items]
Period of basis point spread	2.25%
Credit Linked Notes Maturing October 2052 \| Maximum \| Credit Linked Notes
Debt [Line Items]
Period of basis point spread	11.00%
Credit Linked Notes Maturing April 2052 \| Credit Linked Notes
Debt [Line Items]
Period of basis point spread	6.00%	6.00%
Principal	$ 165	$ 170
Debt Issuance Costs	$ 3	3
Weighted average borrowing rate	6.00%
Reference pool balance	$ 3,300	$ 3,400
Credit Linked Notes Maturing April 2052 \| Minimum \| Credit Linked Notes
Debt [Line Items]
Period of basis point spread	2.25%
Credit Linked Notes Maturing April 2052 \| Maximum \| Credit Linked Notes
Debt [Line Items]
Period of basis point spread	15.00%
Credit Linked Notes Maturing July 2059 \| Credit Linked Notes
Debt [Line Items]
Period of basis point spread	4.67%	4.67%
Principal	$ 174	$ 180
Debt Issuance Costs	$ 2	2
Weighted average borrowing rate	4.67%
Reference pool balance	$ 3,400	$ 3,500
Credit Linked Notes Maturing July 2059 \| Minimum \| Credit Linked Notes
Debt [Line Items]
Period of basis point spread	3.15%
Credit Linked Notes Maturing July 2059 \| Maximum \| Credit Linked Notes
Debt [Line Items]
Period of basis point spread	8.50%