Leases - Supplemental Balance Sheet Information (Details) - USD ($) $ in Millions	Jun. 30, 2022	Mar. 31, 2022
Operating Lease, Supplemental Balance Sheet Information [Abstract]
Operating right-of-use assets, net	$ 1,025	$ 1,133
Current operating lease liabilities	346	388
Non-current operating lease liabilities	742	815
Total operating lease liabilities	$ 1,088	$ 1,203
Weighted-average operating lease term	4 years 2 months 12 days	4 years 4 months 24 days
Weighted-average operating lease discount rate	3.40%	3.30%
Finance Lease, Supplemental Balance Sheet Information [Abstract]
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Property and equipment, net of accumulated depreciation of $3,917 and $3,998	Property and equipment, net of accumulated depreciation of $3,917 and $3,998
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Short-term debt and current maturities of long-term debt	Short-term debt and current maturities of long-term debt
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Long-term debt, excluding finance lease liabilities	Long-term debt, excluding finance lease liabilities
ROU finance lease assets	$ 534	$ 602
Finance lease, liability, current	267	289
Finance lease, liability, noncurrent	321	354
Total finance lease liabilities	$ 588	$ 643
Weighted-average finance lease term	2 years 9 months 18 days	2 years 9 months 18 days
Weighted-average finance lease discount rate	2.90%	2.90%