Revenue Recognition - Disaggregation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Total revenues	$ 158,116	$ 98,143	$ 452,458	$ 278,627
United States
Disaggregation of Revenue [Line Items]
Total revenues	148,033	93,511	427,804	260,999
Americas, excluding U.S.
Disaggregation of Revenue [Line Items]
Total revenues	1,247	1,081	3,052	2,584
Europe, Middle East, India, Africa
Disaggregation of Revenue [Line Items]
Total revenues	5,598	3,524	14,322	10,584
Asia Pacific and Other
Disaggregation of Revenue [Line Items]
Total revenues	3,238	27	7,280	4,460
Insurance carriers
Disaggregation of Revenue [Line Items]
Total revenues	132,423	78,004	351,218	216,305
Laboratory partners
Disaggregation of Revenue [Line Items]
Total revenues	17,441	13,701	77,575	42,426
Patients
Disaggregation of Revenue [Line Items]
Total revenues	8,252	6,438	23,665	19,896
Licensing and other
Disaggregation of Revenue [Line Items]
Total revenues	$ 7,465	$ 4,857	$ 46,193	$ 17,881