Debt - Schedule of Long-term Debt (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Long-term debt, due within one year	$ 4,509	$ 4,340
Long-term debt, due after one year	11,470	13,230
Long-term debt	15,979	17,570
Secured debt	9,177	10,443
Unsecured debt
Debt Instrument [Line Items]
Long-term debt, due within one year	1,974	1,409
Long-term debt, due after one year	7,950	9,015
Long-term debt	9,924	10,424
Secured debt
Debt Instrument [Line Items]
Long-term debt, due within one year	2,535	2,931
Long-term debt, due after one year	3,520	4,215
Long-term debt	6,055	7,146
Federal Home Loan Bank advances
Debt Instrument [Line Items]
Secured debt	$ 4,600	$ 5,600