Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Apr. 01, 2017
Income Tax Contingency [Line Items]
Income tax expense (benefit)	$ 122	$ (22)	$ 134	$ (38)
Settlement with Taxing Authority | Minimum
Income Tax Contingency [Line Items]
Reasonably possible reduction in liability for uncertain tax positions	14		14
Settlement with Taxing Authority | Maximum
Income Tax Contingency [Line Items]
Reasonably possible reduction in liability for uncertain tax positions	19		19
India
Income Tax Contingency [Line Items]
Deferred tax liability	67		67
HPES
Income Tax Contingency [Line Items]
Net taxes payable					$ 14
Tax indemnification receivable, net uncertain tax positions					111
Tax indemnification receivable, other tax payables					69
Tax indemnification payable, other tax receivables					$ 194
Liability for uncertain tax positions	114		114
Domestic Tax Authority | HPES
Income Tax Contingency [Line Items]
Deferred tax liability	$ 570		$ 570