Derivatives - Derivative Assets and Collateral Received (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Derivative [Line Items]
Gross amounts of recognized assets	$ 352	$ 530
Gross amounts offset in the Balance Sheets	0	0
Net amounts of assets presented in the Balance Sheets	352	530
Derivative liabilities available for offset	(89)	(76)
Collateral received	(238)	(440)
Net amount	25	14
Derivative assets not subject to master netting agreements (current year less than)	1	2
Interest rate derivative contracts
Derivative [Line Items]
Gross amounts of recognized assets	343	522
Gross amounts offset in the Balance Sheets	0	0
Net amounts of assets presented in the Balance Sheets	343	522
Derivative liabilities available for offset	(84)	(73)
Collateral received	(236)	(436)
Net amount	23	13
Forward contracts
Derivative [Line Items]
Gross amounts of recognized assets	9	8
Gross amounts offset in the Balance Sheets	0	0
Net amounts of assets presented in the Balance Sheets	9	8
Derivative liabilities available for offset	(5)	(3)
Collateral received	(2)	(4)
Net amount	$ 2	$ 1