Debt (Details) - USD ($)	Sep. 30, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Total short-term debt	$ 17,315,000,000	$ 18,658,000,000
Unamortized discount	(19,000,000)	9,000,000
Unamortized debt issuance costs	(248,000,000)	(237,000,000)
Fair value adjustments	(637,000,000)	(1,258,000,000)
Total long-term debt	119,346,000,000	110,629,000,000
Total debt	$ 136,661,000,000	$ 129,287,000,000
Average Contractual (interest rate)	4.90%	4.80%
Average Effective (interest rate)	4.90%	4.80%
Debt Carrying Value Fair Value	$ 42,200,000,000	$ 38,700,000,000
Fair value of short-term debt	16,000,000,000.0	15,500,000,000
Discontinued Hedged Debt	(536,000,000)	(681,000,000)
Floating Rate Demand Notes [Member]
Debt Instrument [Line Items]
Total short-term debt	11,710,000,000	10,907,000,000
Other short-term debt [Member]
Debt Instrument [Line Items]
Total short-term debt	4,257,000,000	4,593,000,000
Asset-backed Securities [Member]
Debt Instrument [Line Items]
Total short-term debt	1,348,000,000	3,158,000,000
Unsecured Debt [Member]
Debt Instrument [Line Items]
Notes payable within one year	12,995,000,000	11,755,000,000
Notes payable after one year	52,256,000,000	45,435,000,000
Asset-backed Securities [Member]
Debt Instrument [Line Items]
Notes payable within one year	21,855,000,000	18,851,000,000
Notes payable after one year	$ 33,144,000,000	$ 36,074,000,000
Total short-term debt [Member]
Debt Instrument [Line Items]
Average Contractual (interest rate)	5.10%	5.30%
Average Effective (interest rate)	5.10%	5.30%
Total long-term debt [Member]
Debt Instrument [Line Items]
Average Contractual (interest rate)	4.90%	4.70%
Average Effective (interest rate)	4.90%	4.70%
Fair Value, Nonrecurring [Member] | Level 2 [Member]
Debt Instrument [Line Items]
Fair value of debt	$ 139,158,000,000	$ 130,533,000,000