Revenue Recognition Contract balances (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Sep. 30, 2021
Disaggregation of Revenue [Line Items]
Contract liabilities - current	$ (1,845)		$ (1,637)
Contract with Customer, Liability, Revenue Recognized	751	$ 714
Accounts Receivable [Member]
Disaggregation of Revenue [Line Items]
Contract assets - current	1,806		1,718
Other Noncurrent Assets
Disaggregation of Revenue [Line Items]
Contract assets - noncurrent	98		99
Deferred Revenue [Member]
Disaggregation of Revenue [Line Items]
Contract liabilities - current	(1,845)		(1,637)
Other Noncurrent Liabilities [Member]
Disaggregation of Revenue [Line Items]
Contract liabilities - noncurrent	$ (287)		$ (269)