Debt (Long-term Debt Schedule) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Total long-term debt	$ 17,570	$ 17,762
Subordinated debt	1,500	1,000
Secured debt	10,443	10,124
Unsecured debt
Debt Instrument [Line Items]
Fixed rate	10,327	9,929
Hedge basis adjustments	97	108
Total long-term debt	$ 10,424	$ 10,037
Weighted average stated interest rate	6.03%	5.08%
Unsecured debt | Minimum
Debt Instrument [Line Items]
Interest rate	0.60%	0.60%
Unsecured debt | Maximum
Debt Instrument [Line Items]
Interest rate	8.00%	8.00%
Secured debt
Debt Instrument [Line Items]
Fixed rate	$ 7,031	$ 7,603
Hedge basis adjustments	2	4
Variable rate	113	118
Total long-term debt	$ 7,146	$ 7,725
Weighted average stated interest rate	3.31%	2.71%
Variable interest entity debt	$ 1,500	$ 2,400
Secured debt | Minimum
Debt Instrument [Line Items]
Interest rate	0.89%	0.72%
Secured debt | Maximum
Debt Instrument [Line Items]
Interest rate	5.29%	5.29%
Federal Home Loan Bank advances
Debt Instrument [Line Items]
Secured debt	$ 5,600	$ 5,300