Acquisitions and Divestitures - Narrative (Details) $ in Millions	9 Months Ended
Jun. 30, 2019 USD ($) service_center_store numberOfFranchiseServiceCenters numberOfFormerFranchiseCenters	Jun. 30, 2018 USD ($) service_center_store numberOfFormerFranchiseCenters
Business Acquisition [Line Items]
Number of service center stores acquired	54	63
Consideration for acquisition \| $	$ 50	$ 71
Number of former franchise service centers acquired \| numberOfFormerFranchiseCenters	5	60
Number of service center stores acquired in single and multi-store transactions	18
Oil Changers, Inc.
Business Acquisition [Line Items]
Number of franchise service center stores acquired \| numberOfFranchiseServiceCenters	31

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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