Reportable Segments and Revenue Recognition (Remaining Performance Obligation) (Details) - USD ($) $ in Millions	Jun. 30, 2021	Jun. 30, 2020
Leases [Abstract]
Revenue, remaining performance obligation, amount	$ 149	$ 85
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	149	$ 85
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01
Leases [Abstract]
Revenue, remaining performance obligation, amount	48
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 48
Revenue, remaining performance obligation, expected timing of satisfaction, period	6 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Leases [Abstract]
Revenue, remaining performance obligation, amount	$ 62
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 62
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Leases [Abstract]
Revenue, remaining performance obligation, amount	$ 24
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 24
Revenue, remaining performance obligation, expected timing of satisfaction, period	2 years