Revenues (Narrative) (Details) - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Deferred revenue		$ 2.3
Revenues recognized	$ 1.8
Transaction price allocated to remaining performance obligations	$ 29.8
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Expected timing of revenue recognition	24 months
Expected timing of revenue recognition, percent	50.00%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Expected timing of revenue recognition
Expected timing of revenue recognition, percent	50.00%