Reportable Segments and Major Concentration Data - Additional Information (Detail) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2019 USD ($) Customer	Sep. 30, 2018 USD ($) Customer	Sep. 30, 2017 USD ($)
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 50,846	$ 48,440	$ 50,248	$ 51,480	$ 53,100	$ 51,737	$ 56,451	$ 52,283	$ 201,014	$ 213,571	$ 200,771
Identifiable assets	325,478				251,377				325,478	251,377	249,777
Diagnostics [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									$ 136,682	$ 150,454	$ 143,521
Customer Concentration Risk [Member] | Two Diagnostic Distributor Customers [Member] | Consolidated Accounts Receivable [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of major customers | Customer									2	2
Concentration risk percentage									13.00%	12.00%
Third-Party Vendor [Member] | Segment, Third-Party Sales Revenue [Member] | Diagnostics [Member] | Two Foodborne Products [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk percentage									9.00%	9.00%	10.00%
Foreign Customers, Combined International for Diagnostics and Life Science [Member] | Segment, Third-Party Sales Revenue [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									$ 76,430	$ 72,548	$ 66,682
Product Concentration Risk [Member] | Segment, Third-Party Sales Revenue [Member] | Three Product Families [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk percentage									57.00%	59.00%	60.00%
United Kingdom [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Identifiable assets	22,963				14,816				$ 22,963	$ 14,816
United Kingdom [Member] | Diagnostics [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									2,397	2,340	$ 1,778
Germany [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Identifiable assets	7,141				7,706				7,141	7,706
Italy [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Identifiable assets	7,557				7,334				7,557	7,334
Italy [Member] | Diagnostics [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									10,898	10,398	$ 9,004
Australia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Identifiable assets	$ 1,392				$ 3,543				$ 1,392	$ 3,543