Basis of Presentation and Summary of Significant Accounting Policies - Goodwill and Indefinite-Lived Intangible Asset Impairments (Details)	12 Months Ended
	Sep. 30, 2019
Customer relationships | Maximum
Finite-Lived Intangible Assets [Line Items]
Useful life (years)	14 years
Customer relationships | Minimum
Finite-Lived Intangible Assets [Line Items]
Useful life (years)	6 years
Other intangible assets | Maximum
Finite-Lived Intangible Assets [Line Items]
Useful life (years)	20 years
Other intangible assets | Minimum
Finite-Lived Intangible Assets [Line Items]
Useful life (years)	1 year