Share-Based Compensation - Components of Share-Based Compensation Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 182	$ 162	$ 161
Tax benefit for share-based compensation expense	(72)	(87)	(35)
Share-based compensation expense, net of tax	110	75	126
Tax expense (benefit), share-based payment arrangement	(37)	(58)	(10)
Restricted stock unit awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	168	149	148
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	0	0	2
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 14	$ 13	$ 11