Restructuring 1 (Details) $ in Millions	6 Months Ended
	Sep. 30, 2018 USD ($)
Accrued restructuring severance and exit costs activity
Accrued balance at March 31, 2018	$ 7
Accrued balance at September 30, 2018	70
Employee Severance
Accrued restructuring severance and exit costs activity
Accrued balance at March 31, 2018	0
Expense	82
Change in estimate	(6)
Payments	(44)
Accretion and other	0
Accrued balance at September 30, 2018	32
Facility Exit
Accrued restructuring severance and exit costs activity
Accrued balance at March 31, 2018	7
Expense	37
Change in estimate	0
Payments	(6)
Accretion and other	0
Accrued balance at September 30, 2018	$ 38