Intangible Assets - Schedule of Intangible Assets (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Mar. 31, 2019	Sep. 30, 2018	Dec. 31, 2018
Intangible Assets [Line Items]
Definite-lived intangible assets, Accumulated Amortization	$ (14,619)	$ (13,457)
Intangible assets, Gross Carrying Amount	30,639	31,140
Intangible assets, Net	$ 16,020	$ 17,683
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	$ 17,687	$ 18,086
Definite-lived intangible assets, Accumulated Amortization	(10,022)	(9,377)
Definite-lived intangible assets, Net	$ 7,665	$ 8,709
Developed Technology [Member]
Intangible Assets [Line Items]
Definite-lived intangible assets, Weighted Average Original Life (Years)	11 years 6 months	11 years 6 months
Definite-lived intangible assets, Gross Carrying Amount	$ 9,563	$ 9,656
Definite-lived intangible assets, Accumulated Amortization	(2,780)	(2,361)
Definite-lived intangible assets, Net	$ 6,783	$ 7,295
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	(173)	(150)
Definite-lived intangible assets, Net	$ 57	$ 80
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	(1,644)	(1,569)
Definite-lived intangible assets, Net	677	752
Definite-Lived Intangible Assets [Member]
Intangible Assets [Line Items]
Definite-lived intangible assets, Gross Carrying Amount	29,801	30,293
Definite-lived intangible assets, Accumulated Amortization	(14,619)	(13,457)
Definite-lived intangible assets, Net	$ 15,182	16,836
In-Process Research and Development [Member]
Intangible Assets [Line Items]
Indefinite-lived intangible assets, Net		267	$ 258
Trademarks and Trade Names [Member]
Intangible Assets [Line Items]
Indefinite-lived intangible assets, Net		$ 580	$ 580