Derivatives - Derivative Liabilities and Collateral Pledged (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Derivative [Line Items]
Gross amounts of recognized liabilities	$ 130	$ 125
Derivative assets available for offset	0	0
Derivative liability	130	125
Derivative assets  available for offset	(51)	(21)
Collateral pledged	(21)	(82)
Net amount	58	22
Derivative liabilities not subject to master netting agreements	17	22
Derivatives, interest rate contracts
Derivative [Line Items]
Gross amounts of recognized liabilities	95	60
Derivative assets available for offset	0	0
Derivative liability	95	60
Derivative assets  available for offset	(31)	(7)
Collateral pledged	(9)	(31)
Net amount	55	22
Forward contracts
Derivative [Line Items]
Gross amounts of recognized liabilities	35	65
Derivative assets available for offset	0	0
Derivative liability	35	65
Derivative assets  available for offset	(20)	(14)
Collateral pledged	(12)	(51)
Net amount	$ 3	$ 0