Segment Reporting - Reportable Revenues by Geographic Regions (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Segment Reporting Information [Line Items]
Total revenue	$ 79,416	$ 67,400
United States
Segment Reporting Information [Line Items]
Total revenue	75,989	63,804
Europe
Segment Reporting Information [Line Items]
Total revenue	2,252	2,283
Rest of World
Segment Reporting Information [Line Items]
Total revenue	1,175	1,313
Testing services revenue
Segment Reporting Information [Line Items]
Total revenue	66,444	59,281
Testing services revenue | United States
Segment Reporting Information [Line Items]
Total revenue	66,223	59,021
Testing services revenue | Rest of World
Segment Reporting Information [Line Items]
Total revenue	221	260
Product revenue
Segment Reporting Information [Line Items]
Total revenue	6,788	5,778
Product revenue | United States
Segment Reporting Information [Line Items]
Total revenue	3,613	2,495
Product revenue | Europe
Segment Reporting Information [Line Items]
Total revenue	2,242	2,252
Product revenue | Rest of World
Segment Reporting Information [Line Items]
Total revenue	933	1,031
Patient and digital solutions revenue
Segment Reporting Information [Line Items]
Total revenue	6,184	2,341
Patient and digital solutions revenue | United States
Segment Reporting Information [Line Items]
Total revenue	6,153	2,288
Patient and digital solutions revenue | Europe
Segment Reporting Information [Line Items]
Total revenue	10	31
Patient and digital solutions revenue | Rest of World
Segment Reporting Information [Line Items]
Total revenue	$ 21	$ 22