Business Acquisitions Business Acquisitions - Current Year (Details) - USD ($)	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2020
Business Acquisition [Line Items]
Share Price			$ 33.19
Number of Years in Measurement Period from Acquisition Date to Change Underlying Assumptions	5 years	5 years 9 months 18 days
Other Acquisitions [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross	$ 19,700,000	$ 28,500,000
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net	8,800,000	15,700,000
Identifiable Intangible Assets Acquired	10,500,000	11,200,000
Cash and Cash Equivalents [Member] | Other Acquisitions [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross	17,800,000	26,500,000
Contingent Consideration Payments [Member] | Other Acquisitions [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross	$ 1,500,000	$ 2,000,000.0