Goodwill and Intangible Assets - Components of Identifiable Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Sep. 30, 2021
Finite-Lived Intangible Assets [Line Items]
Cost	$ 331,715	$ 331,606
Accumulated Amortization	153,126	145,072
Net Book Value	178,589	186,534
Patents
Finite-Lived Intangible Assets [Line Items]
Cost	1,235	1,242
Accumulated Amortization	1,026	1,002
Net Book Value	209	240
Completed Technology
Finite-Lived Intangible Assets [Line Items]
Cost	75,554	75,527
Accumulated Amortization	34,176	32,383
Net Book Value	41,378	43,144
Trademarks and Trade Names
Finite-Lived Intangible Assets [Line Items]
Cost	424	424
Accumulated Amortization	37	33
Net Book Value	387	391
Noncompete Agreements
Finite-Lived Intangible Assets [Line Items]
Cost	681	681
Accumulated Amortization	297	249
Net Book Value	384	432
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Cost	253,577	253,486
Accumulated Amortization	117,346	111,159
Net Book Value	136,231	142,327
Other Intangible Assets
Finite-Lived Intangible Assets [Line Items]
Cost	244	246
Accumulated Amortization	$ 244	$ 246