Significant Accounting Policies - Narrative (Details) $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2019 USD ($) numberOfSegments numberOfPrincipalActivities	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Oct. 01, 2019 USD ($)	Oct. 01, 2018 USD ($)
Property, Plant and Equipment [Line Items]
Deferred rent	$ 5				$ 3				$ 5	$ 3
Number of principal activities | numberOfPrincipalActivities									3
Number of reportable segments | numberOfSegments									3
Sales	629	$ 613	$ 591	$ 557	594	$ 577	$ 569	$ 545	$ 2,390	2,285	$ 2,084
Sales rebates and discounts									346	357	360
Reserves for customer programs and incentives	72				57				72	57
Shipping and handling costs recorded in sales									10	10	16
Advertising costs									73	63	61
Research and development costs									13	14	13
Increase in retained deficit from adoption of new accounting guidance	284				$ 399				284	399			$ 412
Capitalized implementation costs for cloud computing arrangements	$ 4								$ 4
Sales at a point in time
Property, Plant and Equipment [Line Items]
Percentage of revenue recognized									98.00%
Sales									$ 2,346
Franchised revenues transferred over time
Property, Plant and Equipment [Line Items]
Percentage of revenue recognized									2.00%
Sales									$ 44
ASU 2014-09
Property, Plant and Equipment [Line Items]
Increase in retained deficit from adoption of new accounting guidance													$ 13
Franchise
Property, Plant and Equipment [Line Items]
Sales									$ 44	$ 29	$ 28
Minimum
Property, Plant and Equipment [Line Items]
Payment terms									30 days
Expected timing of satisfaction for revenue performance obligations	10 years								10 years
Minimum | ASU 2016-02 | Scenario, Forecast
Property, Plant and Equipment [Line Items]
Incremental operating lease right-of-use assets												$ 220
Operating lease liabilities												210
Minimum | Buildings
Property, Plant and Equipment [Line Items]
Estimated useful life of property, plant and equipment									5 years
Minimum | Machinery and equipment
Property, Plant and Equipment [Line Items]
Estimated useful life of property, plant and equipment									5 years
Maximum
Property, Plant and Equipment [Line Items]
Payment terms									60 days
Expected timing of satisfaction for revenue performance obligations	15 years								15 years
Maximum | ASU 2016-02 | Scenario, Forecast
Property, Plant and Equipment [Line Items]
Incremental operating lease right-of-use assets												235
Operating lease liabilities												$ 225
Maximum | Buildings
Property, Plant and Equipment [Line Items]
Estimated useful life of property, plant and equipment									25 years
Maximum | Machinery and equipment
Property, Plant and Equipment [Line Items]
Estimated useful life of property, plant and equipment									30 years