Revenue Recognition - Narrative (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Increase (decrease) in contract assets	$ (48)
Increase in contract liabilities	248
Revenue recognized	1,500	$ 1,500
Revenue, remaining performance obligation	$ 16,900		$ 16,400
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, percentage			91.00%
Remaining performance obligation, expected timing of satisfaction period			24 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, percentage	90.00%
Remaining performance obligation, expected timing of satisfaction period	24 months