Pension and Other Benefit Plans - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017	Oct. 31, 2016	May 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Net projected benefit obligations					$ 489
Net projected assets	$ 247				419
Other assets					7
Other long-term liabilities					$ 77
Defined contribution plan expense	33	$ 15	$ 1	$ 3
Deferred compensation liability included in other long-term liabilities	$ 13
Enterprise Services LLC Deferred Compensation Plan
Defined Benefit Plan Disclosure [Line Items]
Percentage of eligible deferred cash compensation	100.00%
Management | Enterprise Services LLC Deferred Compensation Plan
Defined Benefit Plan Disclosure [Line Items]
Percentage of eligible deferred cash compensation	80.00%