Pension and Other Benefit Plans - Pension Plan, Reconciliation of Changes in PBO and Fair Value of Plan Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Projected benefit obligation at beginning of year	$ 12,436	$ 10,150
Service cost	88	91	$ 92
Interest cost	203	245	237
Plan participants’ contributions	30	31
Amendments	(12)	(9)
Business/contract acquisitions/divestitures	(2)	11
Contractual termination benefits	4	13
Settlement/curtailment	(76)	(37)
Actuarial (gain) loss	(831)	1,262
Benefits paid	(458)	(393)
Foreign currency exchange rate changes	(485)	1,084
Other	(35)	(12)
Projected benefit obligation at end of year	$ 10,862	$ 12,436	10,150
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate	2.70%	2.00%
Rates of increase in compensation levels	2.90%	2.50%
Interest Crediting Rate	4.00%	4.00%
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	$ 13,425	$ 11,090
Actual return on plan assets	441	1,401
Employer contribution	161	117
Plan participants’ contributions	30	31
Benefits paid	(458)	(393)
Business/contract acquisitions/divestitures	0	0
Contractual termination benefits	4	7
Plan settlement	(66)	(31)
Foreign currency exchange rate changes	(566)	1,224
Other	(19)	(21)
Fair value of plan assets at end of year	12,952	13,425	$ 11,090
Funded status at end of year	$ 2,090	$ 989