Revenue - Performance Obligations (Details) $ in Millions	Jan. 31, 2019 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-02-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Expected revenue	$ 71
Expected revenue, period	9 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-11-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Expected revenue	$ 77
Expected revenue, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-11-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Expected revenue	$ 58
Expected revenue, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-11-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Expected revenue	$ 35
Expected revenue, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-11-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Expected revenue	$ 18
Expected revenue, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-11-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Expected revenue	$ 10
Expected revenue, period	1 year