Revenue (Remaining Performance Obligations to be Recognized as Revenue) (Details) $ in Billions	Dec. 31, 2020 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total backlog	$ 89.5
Revenue, remaining performance obligation, percentage recognized	35.00%
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue, remaining performance obligation, percentage recognized	30.00%
Revenue, remaining performance obligation, expected timing of satisfaction, period	2 years