Other Borrowings - Outstanding Credit Linked Noted Issuances (Details) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2026 USD ($) class	Dec. 31, 2025 USD ($)
Debt [Line Items]
Classes of notes \| class	6
Credit Linked Notes
Debt [Line Items]
Principal	$ 401	$ 407
Unamortized 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	$ 79	$ 80
Unamortized Debt Issuance Costs	$ 2	2
Weighted average borrowing rate	7.80%
Reference pool balance	$ 1,500	$ 1,600
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	$ 157	$ 160
Unamortized Debt Issuance Costs	$ 3	3
Weighted average borrowing rate	6.00%
Reference pool balance	$ 3,200	$ 3,200
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	$ 165	$ 167
Unamortized Debt Issuance Costs	$ 2	2
Weighted average borrowing rate	4.67%
Reference pool balance	$ 3,200	$ 3,300
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%