Reportable Segments (Remaining Performance Obligations) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Jun. 30, 2019
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 85	$ 112
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 52
Revenue, remaining performance obligation, expected timing of satisfaction, period	6 months