Restructuring, Impairment, and Related Charges, Net - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Restructuring Cost and Reserve [Line Items]
Restructuring, impairment, and related charges, net	$ 209	$ 281	$ 334
Restructuring charges	209	245	219
Long-lived asset impairment charges, before tax	0
International
Restructuring Cost and Reserve [Line Items]
Long-lived asset impairment charges, before tax		36
International | Retail Pharmacy Reporting Unit
Restructuring Cost and Reserve [Line Items]
Long-lived asset impairment charges, before tax			115
U.K. | International
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0	57
Strategic Growth Initiative Plan - Operational Efficiencies and Cost Optimization
Restructuring Cost and Reserve [Line Items]
Restructuring costs, anticipated total charges	125
Restructuring charges	$ 60
Restructuring Plan, Remote Work Transitioning
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 124
Strategic Growth Initiative Plan - Additional Global Reorganization and Business Consolidation Programs | Employee Severance, Accelerated Depreciation and Project Consulting Fees
Restructuring Cost and Reserve [Line Items]
Restructuring charges			62
Strategic Growth Initiative Plan - Relocation of Corporate Headquarters | Employee Retention Expenses, Asset Impairments and Accelerated Depreciation
Restructuring Cost and Reserve [Line Items]
Restructuring charges			$ 28