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, 2018	Apr. 01, 2018	Mar. 31, 2018
Revenue from Contract with Customer [Abstract]
Contract with Customer, Asset, Net	$ 806		$ 432
Billed trade receivables	2,591		2,559
Unbilled trade receivables	918		1,250
Contract with Customer, Liability	1,011		$ 1,104
Sales commissions, opening balance	1,219
Sales commissions, additions	874
Capitalized Contract Cost, Amortization	(596)
Costs to acquire a customer contract	1,497	$ 1,219
Revenue recognized from contract liability	$ 986