Accrued Expenses and Other Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Sep. 30, 2020
Payables and Accruals [Abstract]
Accrued Salaries, Current	$ 79,110	$ 67,766
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Accrued expenses and other liabilities	Accrued expenses and other liabilities
Obligation under operating leases	$ 13,316	$ 12,767
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Accrued expenses and other liabilities	Accrued expenses and other liabilities
Less current installments of obligations under finance leases	$ 12,093	$ 11,362
Accrued Sales Commission, Current	10,031	9,270
Accrual for Taxes Other than Income Taxes, Current	4,575	5,316
Accrued Insurance, Current	3,720	3,954
Estimated Litigation Liability, Current	2,938	2,580
Restructuring Reserve, Current	304	970
Business Combination, Contingent Consideration, Liability, Current	150	295
Other Accrued Liabilities, Current	33,576	24,393
Accrued expenses and other liabilities	160,367	143,389
Cash Flow Hedge Derivative Instrument Liabilities at Fair Value	$ 554	$ 4,716