Intangible Assets - Schedule of Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Sep. 30, 2017
Intangible Assets [Line Items]
Definite-lived intangible assets, Accumulated Amortization	$ (12,350)	$ (10,838)
Intangible assets, Gross Carrying Amount	32,075	31,400
Intangible assets, Net	$ 19,725	$ 20,562
Customer Lists and Relationships [Member]
Intangible Assets [Line Items]
Definite-lived intangible assets, Weighted Average Original Life (Years)	8 years 10 months 24 days	8 years 10 months 24 days
Definite-lived intangible assets, Gross Carrying Amount	$ 18,832	$ 18,293
Definite-lived intangible assets, Accumulated Amortization	(8,777)	(7,834)
Definite-lived intangible assets, Net	$ 10,055	$ 10,459
Developed Technology [Member]
Intangible Assets [Line Items]
Definite-lived intangible assets, Weighted Average Original Life (Years)	11 years 6 months	11 years 8 months 12 days
Definite-lived intangible assets, Gross Carrying Amount	$ 9,829	$ 9,297
Definite-lived intangible assets, Accumulated Amortization	(1,950)	(1,478)
Definite-lived intangible assets, Net	$ 7,879	$ 7,819
Non-compete [Member]
Intangible Assets [Line Items]
Definite-lived intangible assets, Weighted Average Original Life (Years)	5 years	5 years
Definite-lived intangible assets, Gross Carrying Amount	$ 230	$ 230
Definite-lived intangible assets, Accumulated Amortization	(127)	(103)
Definite-lived intangible assets, Net	$ 103	$ 127
Patents and Other [Member]
Intangible Assets [Line Items]
Definite-lived intangible assets, Weighted Average Original Life (Years)	16 years 6 months	16 years 6 months
Definite-lived intangible assets, Gross Carrying Amount	$ 2,321	$ 2,321
Definite-lived intangible assets, Accumulated Amortization	(1,496)	(1,423)
Definite-lived intangible assets, Net	825	898
Definite-Lived Intangible Assets [Member]
Intangible Assets [Line Items]
Definite-lived intangible assets, Gross Carrying Amount	31,212	30,141
Definite-lived intangible assets, Accumulated Amortization	(12,350)	(10,838)
Definite-lived intangible assets, Net	18,862	19,303
In-Process Research and Development [Member]
Intangible Assets [Line Items]
Indefinite-lived intangible assets, Net	283	679
Trademarks and Trade Names [Member]
Intangible Assets [Line Items]
Indefinite-lived intangible assets, Net	$ 580	$ 580