Debt (Scheduled Remaining Maturity of Long-term Debt) (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Long-term debt, maturities, repayments of principal in next 12 months	$ 2,010
Long-term debt, maturities, repayments of principal in year two	4,798
Long-term debt, maturities, repayments of principal in year three	4,704
Long-term debt, maturities, repayments of principal in year four	2,063
Long-term debt, maturities, repayments of principal in year five	1,969
Long-term debt, maturities, repayments of principal after year five	4,552
Total long-term debt	20,096	$ 17,762
Unsecured debt
Debt Instrument [Line Items]
Long-term debt, maturities, repayments of principal in next 12 months	1,203
Long-term debt, maturities, repayments of principal in year two	1,410
Long-term debt, maturities, repayments of principal in year three	2,411
Long-term debt, maturities, repayments of principal in year four	72
Long-term debt, maturities, repayments of principal in year five	1,443
Long-term debt, maturities, repayments of principal after year five	4,277
Total long-term debt	10,816	10,037
Secured debt
Debt Instrument [Line Items]
Total long-term debt	9,280	$ 7,725
Long-term debt | Unsecured debt
Debt Instrument [Line Items]
Long-term debt, maturities, repayments of principal in next 12 months	1,219
Long-term debt, maturities, repayments of principal in year two	1,478
Long-term debt, maturities, repayments of principal in year three	2,485
Long-term debt, maturities, repayments of principal in year four	154
Long-term debt, maturities, repayments of principal in year five	1,537
Long-term debt, maturities, repayments of principal after year five	4,790
Total long-term debt	11,663
Long-term debt | Secured debt
Debt Instrument [Line Items]
Long-term debt, maturities, repayments of principal in next 12 months	807
Long-term debt, maturities, repayments of principal in year two	3,388
Long-term debt, maturities, repayments of principal in year three	2,293
Long-term debt, maturities, repayments of principal in year four	1,991
Long-term debt, maturities, repayments of principal in year five	526
Long-term debt, maturities, repayments of principal after year five	275
Total long-term debt	9,280
Original issue discount | Unsecured debt
Debt Instrument [Line Items]
Debt instrument, unamortized discount	(847)
Original issue discount | Unsecured debt | 2023
Debt Instrument [Line Items]
Debt instrument, unamortized discount, current	(16)
Original issue discount | Unsecured debt | 2024
Debt Instrument [Line Items]
Debt instrument, unamortized discount, noncurrent	(68)
Original issue discount | Unsecured debt | 2025
Debt Instrument [Line Items]
Debt instrument, unamortized discount, noncurrent	(74)
Original issue discount | Unsecured debt | 2026
Debt Instrument [Line Items]
Debt instrument, unamortized discount, noncurrent	(82)
Original issue discount | Unsecured debt | 2027
Debt Instrument [Line Items]
Debt instrument, unamortized discount, noncurrent	(94)
Original issue discount | Unsecured debt | 2028 and thereafter
Debt Instrument [Line Items]
Debt instrument, unamortized discount, noncurrent	$ (513)