Segments of Business - Schedule of Segment Information (Details) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2025 USD ($) segment	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($) segment	Sep. 30, 2024 USD ($)
Segment revenues
Total revenues	$ 103,150	$ 93,651	$ 200,977	$ 172,934
Other segment expense, net
Total other segment expense, net	101,474	92,795	198,008	170,816
Segment operating profit
Subtotal	1,676	856	2,969	2,118
Interest expense	(74)	(78)	(123)	(153)
Income before income taxes	1,395	534	2,446	1,618
Segment depreciation and amortization
Total segment depreciation and amortization	188	163	345	332
Segment expenditures for long-lived assets
Total segment expenditures for long-lived assets	$ 196	218	$ 385	385
Number of reportable segments | segment	4		4
Provision for bad debts			$ 232	(169)
Canadian businesses held for sale			0	638
Restructuring charges	$ 63	234	110	244
Severance and employee-related costs, net	9	149	13	148
Gain associated with equity investments		(15)		95
North American Pharmaceutical
Segment expenditures for long-lived assets
Provision for bad debts		(203)	189	(203)
North American Pharmaceutical | Held-for-sale | Canadian retail disposal group
Segment expenditures for long-lived assets
Canadian businesses held for sale		593		593
Operating Segments | North American Pharmaceutical
Segment revenues
Total revenues	86,481	80,018	169,210	146,366
Other segment expense, net
Total other segment expense, net	85,629	79,671	167,764	145,317
Segment operating profit
Subtotal	852	347	1,446	1,049
Segment depreciation and amortization
Total segment depreciation and amortization	32	43	64	91
Segment expenditures for long-lived assets
Total segment expenditures for long-lived assets	$ 74	$ 66	$ 135	$ 96
Revenue derived from services (less than) (as a percent)	1.00%	1.00%	1.00%	1.00%
Net cash proceeds from settlements	$ 0	$ 63	$ 8	$ 153
Restructuring charges	6	63	7	65
Severance and employee-related costs, net	4	1	4	1
Operating Segments | North American Pharmaceutical | National Prescription Opioid Litigation
Segment expenditures for long-lived assets
Pre-tax charges related to estimated litigation liability				57
Operating Segments | Oncology & Multispecialty
Segment revenues
Total revenues	12,044	9,157	22,702	17,938
Other segment expense, net
Total other segment expense, net	11,712	8,957	22,158	17,590
Segment operating profit
Subtotal	332	200	544	348
Segment depreciation and amortization
Total segment depreciation and amortization	71	37	113	75
Segment expenditures for long-lived assets
Total segment expenditures for long-lived assets	$ 23	$ 19	$ 47	$ 37
Revenue derived from services (less than) (as a percent)	7.00%	7.00%	7.00%	7.00%
Gain from cost and equity method investments	$ 51		$ 51
Loss from equity method investments				$ 43
Operating Segments | Prescription Technology Solutions
Segment revenues
Total revenues	1,376	$ 1,265	2,810	2,506
Other segment expense, net
Total other segment expense, net	1,132	1,060	2,313	2,098
Segment operating profit
Subtotal	244	205	497	408
Segment depreciation and amortization
Total segment depreciation and amortization	20	22	41	43
Segment expenditures for long-lived assets
Total segment expenditures for long-lived assets	$ 0	$ 3	$ 1	$ 7
Revenue derived from services (less than) (as a percent)	37.00%	37.00%	37.00%	37.00%
Restructuring charges	$ 0	$ 1	$ 0	$ 5
Severance and employee-related costs, net	0	0	0	0
Operating Segments | Medical-Surgical Solutions
Segment revenues
Total revenues	2,947	2,946	5,648	5,578
Other segment expense, net
Total other segment expense, net	2,727	2,855	5,207	5,295
Segment operating profit
Subtotal	220	91	441	283
Segment depreciation and amortization
Total segment depreciation and amortization	23	22	45	44
Segment expenditures for long-lived assets
Total segment expenditures for long-lived assets	$ 32	$ 42	$ 57	$ 93
Revenue derived from services (less than) (as a percent)	1.00%	1.00%	1.00%	1.00%
Restructuring charges	$ 19	$ 147	$ 36	$ 150
Severance and employee-related costs, net	5	144	10	144
Other
Segment revenues
Total revenues	302	265	607	546
Other segment expense, net
Total other segment expense, net	274	252	566	516
Segment operating profit
Subtotal	28	13	41	30
Segment depreciation and amortization
Total segment depreciation and amortization	1	5	4	10
Segment expenditures for long-lived assets
Total segment expenditures for long-lived assets	4	4	5	9
Corporate
Segment operating profit
Corporate expenses, net	(207)	(244)	(400)	(347)
Segment depreciation and amortization
Total segment depreciation and amortization	41	34	78	69
Segment expenditures for long-lived assets
Total segment expenditures for long-lived assets	63	84	140	143
Restructuring charges	38	23	67	24
Severance and employee-related costs, net	$ 0	4	$ (1)	3
Gain associated with equity investments				95
Corporate | Canadian retail disposal group
Segment expenditures for long-lived assets
Other comprehensive loss		$ 50		50
Corporate | National Prescription Opioid Litigation
Segment expenditures for long-lived assets
Pre-tax charges related to estimated litigation liability				$ 51