Revenues (Narrative) (Details) $ in Billions	9 Months Ended
	Sep. 30, 2020 USD ($)
Revenue from Contract with Customer [Abstract]
Deferred revenue recognized during period	$ 1.6
Revenue not yet recognized	$ 19.0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Expected timing of revenue recognition	24 months
Expected timing of revenue recognition, percentage	50.00%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Expected timing of revenue recognition
Expected timing of revenue recognition, percentage	50.00%