Pension and Other Benefit Plans - Schedule of Components of Net Periodic Pension Expense (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Sep. 30, 2018	Sep. 30, 2018
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 0	$ 0
Interest cost	5	6
Expected return on assets	(7)	(9)
Net periodic pension benefit	$ (2)	$ (3)