Pension and Other Benefit Plans - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Mar. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Employer contribution	$ 23	$ 33
Expected employer contributions during remainder of Fiscal 2020	48	48
Contractual termination benefit	6	17
Deferred compensation plan, liability	$ 55	$ 55	$ 59
Non-employee directors
Defined Benefit Plan Disclosure [Line Items]
Maximum deferral percentage		100.00%