Revenue Recognition - Performance Obligation Satisfaction Period (Details) $ in Millions	Sep. 30, 2020 USD ($)
Revenue from Contract with Customer [Abstract]
Remaining performance obligation	$ 2,390
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-10-01
Revenue from Contract with Customer [Abstract]
Remaining performance obligation	$ 1,300
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation expected recognition period for three-fourths of remaining obligation	12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-10-01
Revenue from Contract with Customer [Abstract]
Remaining performance obligation	$ 1,090
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation expected recognition period for three-fourths of remaining obligation