Acquisitions, Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2017	Sep. 30, 2017
Acquired Finite-Lived Intangible Assets [Line Items]
Accumulated Amortization	$ (664)	$ (591)
Indefinite-lived Intangible Assets [Line Items]
Gross	2,726	2,720
Net	$ 2,062	2,129
Maximum up-front sales incentives amortization period	15 years
Weighted-average amortization period remaining for up-front sales incentives	10 years
Trademarks and tradenames
Indefinite-lived Intangible Assets [Line Items]
Intangible assets with indefinite lives	$ 47	47
Developed technology and patents
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	807	806
Accumulated Amortization	(274)	(256)
Net	533	550
Backlog
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	6	6
Accumulated Amortization	(5)	(5)
Net	1	1
Customer relationships - Acquired
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	1,495	1,495
Accumulated Amortization	(263)	(213)
Net	1,232	1,282
Customer relationships - Up-front sales incentives
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	340	336
Accumulated Amortization	(97)	(93)
Net	243	243
License agreements
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	16	15
Accumulated Amortization	(11)	(10)
Net	5	5
Trademarks and tradenames
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	15	15
Accumulated Amortization	(14)	(14)
Net	$ 1	$ 1