Revenues from Contracts with Customers Revenues from Contracts with Customers - Schedule of Contract Assets and Contract Liabilities (Details) - USD ($) $ in Millions	9 Months Ended
	Dec. 31, 2019	Mar. 31, 2019
Revenue from Contract with Customer [Abstract]
Document Period End Date	Dec. 31, 2019
Contract with Customer, Asset, Net	$ 1,081	$ 928
Billed trade receivables	2,654	2,690
Unbilled trade receivables	1,230	945
Contract with Customer, Liability	1,051	1,009
Sales commissions, opening balance	1,559
Sales commissions, additions	958
Capitalized Contract Cost, Amortization	(709)
Costs to acquire a customer contract	$ 1,808	$ 1,559