Revenue Related to Contracts with Customers - Narrative (Details) - USD ($) $ in Billions	Sep. 30, 2020	Sep. 30, 2019
Revenue from Contract with Customer [Abstract]
Performance obligations expected to be satisfied	$ 23.0	$ 22.2
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 | Period one
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied, percent	49.00%
Performance obligations expected to be satisfied, expected timing	2 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 | Period two
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied, percent	68.00%
Performance obligations expected to be satisfied, expected timing	5 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 | Period three
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied, percent	92.00%
Performance obligations expected to be satisfied, expected timing	15 years