Accounting Policies and Supplemental Disclosures - Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2025	Mar. 31, 2024
SUPPLEMENTAL CASH FLOW INFORMATION:
Cash paid for interest on debt, net of capitalized interest	$ 236	$ 269	$ 1,825	$ 2,475
Cash paid for operating leases	3,562	3,332	12,571	11,318
Cash paid for interest on finance leases	71	74	284	301
Cash paid for interest on financing obligations	55	64	210	201
Cash paid for income taxes, net of refunds	877	458	12,727	11,018
Assets acquired under operating leases	4,321	3,753	15,992	14,179
Property and equipment acquired under finance leases, net of remeasurements and modifications	54	42	866	676
Increase (decrease) in property and equipment acquired but not yet paid	$ 3,108	$ 411	$ 9,736	$ 801