Acquisitions Transaction, Integration, Financing and Restructuring Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Business Combinations [Abstract]
Business Combination, Integration Related Costs	$ 237	$ 192	$ 95
Charged to expense	85	526	271
Acquisition-related costs	$ 39	$ 10	$ 59