Goodwill and Intangible Assets Components of Identifiable Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Sep. 30, 2016
Finite-Lived Intangible Assets [Line Items]
Cost	$ 196,974	$ 191,698
Accumulated Amortization	113,542	109,855
Net Book Value	83,432	81,843
Patents
Finite-Lived Intangible Assets [Line Items]
Cost	9,028	7,808
Accumulated Amortization	7,523	7,486
Net Book Value	1,505	322
Completed Technology
Finite-Lived Intangible Assets [Line Items]
Cost	60,385	60,485
Accumulated Amortization	51,927	51,018
Net Book Value	8,458	9,467
Trademarks and Trade Names
Finite-Lived Intangible Assets [Line Items]
Cost	9,139	9,142
Accumulated Amortization	4,392	4,204
Net Book Value	4,747	4,938
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Cost	118,422	114,263
Accumulated Amortization	49,700	47,147
Net Book Value	$ 68,722	$ 67,116