Significant Accounting Policies - Summary of Disaggregation of Revenue by Disease State (Detail) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenue	$ 51,480	$ 52,283
Revenue, % change	(2.00%)
Diagnostics [Member]
Segment Reporting Information [Line Items]
Revenue	$ 36,665	37,490
Revenue, % change	(2.00%)
Diagnostics [Member] | Gastrointestinal Assays [Member]
Segment Reporting Information [Line Items]
Revenue	$ 18,633	20,270
Revenue, % change	(8.00%)
Diagnostics [Member] | Respiratory Illness Assays [Member]
Segment Reporting Information [Line Items]
Revenue	$ 7,977	7,486
Revenue, % change	7.00%
Diagnostics [Member] | Blood Chemistry Assays [Member]
Segment Reporting Information [Line Items]
Revenue	$ 4,466	4,266
Revenue, % change	5.00%
Diagnostics [Member] | Other [Member]
Segment Reporting Information [Line Items]
Revenue	$ 5,589	$ 5,468
Revenue, % change	2.00%