Receivables - Allowance for Doubtful Accounts (Details) - USD ($) $ in Millions	6 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 74
Provisions for losses on accounts receivable	45	$ 0
Other adjustments to allowance and write-off's	39
Ending balance	162
Cumulative Effect, Period of Adoption, Adjustment
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 4