Debt (Long-term Debt) (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Long-term debt, due within one year	$ 4,418	$ 5,869
Long-term debt, due after one year	13,344	11,160
Long-term debt	17,762	17,029
Secured debt	10,124	7,619
Unsecured debt
Debt Instrument [Line Items]
Long-term debt, due within one year	2,023	1,028
Long-term debt, due after one year	8,014	8,382
Long-term debt	10,037	9,410
Secured debt
Debt Instrument [Line Items]
Long-term debt, due within one year	2,395	4,841
Long-term debt, due after one year	5,330	2,778
Long-term debt	7,725	7,619
Federal Home Loan Bank advances
Debt Instrument [Line Items]
Secured debt	$ 5,300	$ 6,300