Reportable Segments and Major Concentration Data - Segment Information (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Net revenues	$ 53,100	$ 51,737	$ 56,451	$ 52,283	$ 49,697	$ 50,140	$ 54,125	$ 46,809	$ 213,571	$ 200,771	$ 196,082
Operating income									31,584	37,382	51,378
Depreciation and amortization									8,688	9,090	7,718
Capital expenditures									4,201	4,467	4,004
Goodwill	54,637				54,926				54,637	54,926	61,982
Other intangible assets	23,113				26,704				23,113	26,704	29,855
Total assets	251,377				249,777				251,377	249,777	252,028
Restructuring and litigation costs									13,051	762
Diagnostics [Member]
Segment Reporting Information [Line Items]
Net revenues									150,454	143,521	145,114
Life Science [Member]
Segment Reporting Information [Line Items]
Net revenues									63,117	57,250	50,968
Operating Segments [Member] | Diagnostics [Member]
Segment Reporting Information [Line Items]
Net revenues									150,454	143,521	145,114
Operating income									29,701	23,848	38,202
Depreciation and amortization									6,557	7,037	5,471
Capital expenditures									2,477	2,554	2,690
Goodwill	35,213				35,213				35,213	35,213	42,608
Other intangible assets	22,068				24,973				22,068	24,973	27,534
Total assets	180,978				180,226				180,978	180,226	185,446
Net revenues									392	389	289
Operating Segments [Member] | Life Science [Member]
Segment Reporting Information [Line Items]
Net revenues									63,117	57,250	50,968
Operating income									14,912	14,086	12,997
Depreciation and amortization									2,131	2,053	2,247
Capital expenditures									1,724	1,913	1,314
Goodwill	19,424				19,713				19,424	19,713	19,374
Other intangible assets	1,045				1,731				1,045	1,731	2,321
Total assets	70,341				69,938				70,341	69,938	66,624
Net revenues									397	537	893
Unallocated Costs and Eliminations [Member]
Segment Reporting Information [Line Items]
Operating income									(13,029)	(552)	179
Total assets	$ 58				$ (387)				58	(387)	(42)
Net revenues									(789)	(926)	$ (1,182)
Unallocated Costs [Member]
Segment Reporting Information [Line Items]
Restructuring and litigation costs									$ 13,051	$ 762