Summary of Significant Accounting Policies - Summary of Disaggregation of Revenue by Disease State (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Revenue	$ 253,667	$ 201,014	$ 213,571
Revenue, % change	26.00%	(6.00%)
Diagnostics [Member]
Segment Reporting Information [Line Items]
Revenue	$ 121,132	$ 136,682	150,454
Revenue, % change	(11.00%)	(9.00%)
Diagnostics [Member] | Gastrointestinal Assays [Member]
Segment Reporting Information [Line Items]
Revenue	$ 55,040	$ 68,982	78,803
Revenue, % change	(20.00%)	(12.00%)
Diagnostics [Member] | Respiratory Illness Assays [Member]
Segment Reporting Information [Line Items]
Revenue	$ 26,694	$ 26,622	28,911
Revenue, % change	0.00%	(8.00%)
Diagnostics [Member] | Blood Chemistry Assays [Member]
Segment Reporting Information [Line Items]
Revenue	$ 17,534	$ 18,639	19,109
Revenue, % change	(6.00%)	(2.00%)
Diagnostics [Member] | Other [Member]
Segment Reporting Information [Line Items]
Revenue	$ 21,864	$ 22,439	$ 23,631
Revenue, % change	(3.00%)	(5.00%)