Revenue from Contracts With Customers - Performance obligations (Details) $ in Millions	Mar. 31, 2019 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Sales expected to be recognized on multi-year contracts in place as of the end of the period	$ 2,072
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Period in which remaining performance obligations expect to be satisfied and revenue recognized	9 months
Sales expected to be recognized on multi-year contracts in place as of the end of the period	$ 1,230
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Period in which remaining performance obligations expect to be satisfied and revenue recognized	0 months
Sales expected to be recognized on multi-year contracts in place as of the end of the period	$ 842