Leases - Supplemental Balance Sheet Information (Details) - USD ($) $ in Millions	Jun. 30, 2023	Mar. 31, 2023
Operating Lease, Supplemental Balance Sheet Information [Abstract]
Operating right-of-use assets, net	$ 849	$ 909
Current operating lease liabilities	303	317
Non-current operating lease liabilities	598	648
Total operating lease liabilities	$ 901	$ 965
Weighted-average operating lease term	3 years 10 months 24 days	3 years 10 months 24 days
Weighted-average operating lease discount rate	4.10%	3.90%
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 $4,166 and $4,111	Property and equipment, net of accumulated depreciation of $4,166 and $4,111
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	$ 370	$ 424
Finance lease, liability, current	208	215
Finance lease, liability, noncurrent	267	287
Total finance lease liabilities	$ 475	$ 502
Weighted-average finance lease term	2 years 9 months 18 days	2 years 10 months 24 days
Weighted-average finance lease discount rate	3.50%	3.40%