Revenue Recognition - Remaining Performance Obligation (Details) - Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-07-01 $ in Millions	6 Months Ended
	Sep. 30, 2018 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 28
Remaining performance obligation, expected timing of satisfaction, period	12 months