Debt - Schedule of Short-term Debt (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Short-term Debt [Line Items]
Federal Home Loan Bank	$ 3,350	$ 1,625
Securities sold under agreements to repurchase	529	0
Total short-term borrowings	3,879	1,625
Maturity Within 30 Days
Short-term Debt [Line Items]
Securities sold under agreements to repurchase	429
Maturity 31 to 60 Days
Short-term Debt [Line Items]
Securities sold under agreements to repurchase	100
Unsecured debt
Short-term Debt [Line Items]
Federal Home Loan Bank	0	0
Securities sold under agreements to repurchase	0	0
Total short-term borrowings	0	0
Secured debt
Short-term Debt [Line Items]
Federal Home Loan Bank	3,350	1,625
Securities sold under agreements to repurchase	529	0
Total short-term borrowings	$ 3,879	$ 1,625