Revenue Recognition Contract Assets (Liabilities) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Mar. 31, 2023	Mar. 31, 2023	Sep. 30, 2022
Revenue from Contract with Customer [Abstract]
Unbilled receivables (contract assets)	$ 1,342	$ 1,342	$ 1,390
Customer advances (contract liabilities)	(975)	(975)	(776)
Net contract liabilities	367	367	$ 614
Revenue recognized, included in beginning contract liability	106	441
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Backlog	$ 8,100	$ 8,100