Intangible Assets - Summary of Intangible Assets (Details) - USD ($) $ in Millions	Mar. 31, 2019	Mar. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 1,765	$ 995
Accumulated Amortization	(299)	(98)
Net Carrying Value	1,466	897
Program assets
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	1,525	900
Accumulated Amortization	(194)	(69)
Net Carrying Value	1,331	831
Software
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	87	75
Accumulated Amortization	(58)	(28)
Net Carrying Value	29	47
Developed technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	105
Accumulated Amortization	(22)
Net Carrying Value	83
Backlog
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	22
Accumulated Amortization	(18)
Net Carrying Value	4
Outsourcing contract costs
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	25	20
Accumulated Amortization	(7)	(1)
Net Carrying Value	18	$ 19
Favorable leases
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	1
Accumulated Amortization	0
Net Carrying Value	$ 1