Revenue Recognition - Disaggregation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Total revenues	$ 391,005	$ 302,328	$ 257,654
United States
Disaggregation of Revenue [Line Items]
Total revenues	365,660	260,846	225,931
Americas, excluding U.S.
Disaggregation of Revenue [Line Items]
Total revenues	3,469	3,218	3,472
Europe, Middle East, India, and Africa
Disaggregation of Revenue [Line Items]
Total revenues	14,332	15,434	20,866
Asia Pacific and Other
Disaggregation of Revenue [Line Items]
Total revenues	7,544	22,830	7,385
Insurance carriers
Disaggregation of Revenue [Line Items]
Total revenues	300,220	210,919	193,895
Laboratory partners
Disaggregation of Revenue [Line Items]
Total revenues	58,196	59,876	44,062
Patients
Disaggregation of Revenue [Line Items]
Total revenues	32,589	31,533	19,697
Product
Disaggregation of Revenue [Line Items]
Total revenues	367,211	269,881	240,366
Licensing and other
Disaggregation of Revenue [Line Items]
Total revenues	$ 23,794	$ 32,447	$ 17,288