Income Taxes - Narrative (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
	Mar. 09, 2020	Mar. 31, 2020	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Income Tax Contingency [Line Items]
Income tax expense (benefit) rates (percent)			33.00%	(13.80%)	1.60%
Statutory federal income tax rate (percent)			21.00%	21.00%	21.00%
European businesses held for sale			$ 1,509	$ 0	$ 0
Deferred tax benefit			(34)	908	342
Net discrete tax benefit				105
Valuation allowance			726	864
Increase (decrease) in valuation allowance			138
Unrecognized tax benefits		$ 958	1,523	1,754	958	$ 1,052
Unrecognized tax benefits that would Impact income tax expense and the effective tax rate			1,300
Unrecognized tax benefits, reduction resulting from lapse of applicable statute of limitations			102	12	13
Amount of decrease in unrecognized tax benefits that is reasonably possible in the next twelve months			170
Income tax expense (benefit), before any tax effect, related to accrued interest and penalties			8	9	23
Undistributed earnings of foreign operations			5,000
Accrued interest and penalties on unrecognized tax benefits			108	101
U.K. Businesses (Disposal Group) and Austrian Business
Income Tax Contingency [Line Items]
European businesses held for sale			1,200
Held-for-sale | E.U. Businesses (Disposal Group)
Income Tax Contingency [Line Items]
European businesses held for sale			438
Unrecognized tax benefits, reduction resulting from lapse of applicable statute of limitations			23
Change Healthcare
Income Tax Contingency [Line Items]
Gain from sale of equity method investment	$ 414	414
Change Healthcare | Corporate Joint Venture
Income Tax Contingency [Line Items]
Gain from sale of equity method investment		$ 414			(414)
Federal
Income Tax Contingency [Line Items]
Federal, state and foreign net operating loss carryforwards			303
State
Income Tax Contingency [Line Items]
Federal, state and foreign net operating loss carryforwards			3,900
Foreign Tax Authority
Income Tax Contingency [Line Items]
Federal, state and foreign net operating loss carryforwards			1,500
International
Income Tax Contingency [Line Items]
European businesses held for sale				58	$ 275
National Prescription Opiate Litigation
Income Tax Contingency [Line Items]
Loss contingency accrual, period increase (decrease)			274	8,100
Loss contingency accrual, period increase (decrease), net of tax			237	$ 6,800
Capital Loss Carryforward | Foreign Tax Authority
Income Tax Contingency [Line Items]
Federal, state and foreign net operating loss carryforwards			$ 785