Pension and Other Benefit Plans - Pension Plan, Net Periodic Costs and Other Changes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Retirement Benefits [Abstract]
Service cost	$ 22	$ 23	$ 67	$ 68
Interest cost	50	62	153	181
Expected return on assets	(139)	(163)	(432)	(477)
Amortization of prior service costs	(2)	(2)	(6)	(6)
Contractual termination benefit	(3)	0	(2)	3
Curtailment gain	0	0	0	(9)
Recognition of actuarial loss	7	0	7	11
Net periodic pension income	$ (65)	$ (80)	$ (213)	$ (229)