Revenue Recognition - Disaggregation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Total revenues	$ 98,143	$ 77,909	$ 278,627	$ 219,088
United States
Disaggregation of Revenue [Line Items]
Total revenues	93,511	64,839	260,999	187,515
Americas, excluding U.S.
Disaggregation of Revenue [Line Items]
Total revenues	1,081	806	2,584	2,391
Europe, Middle East, India, Africa
Disaggregation of Revenue [Line Items]
Total revenues	3,524	3,497	10,584	11,819
Asia Pacific and Other
Disaggregation of Revenue [Line Items]
Total revenues	27	8,767	4,460	17,363
Insurance carriers
Disaggregation of Revenue [Line Items]
Total revenues	78,004	51,801	216,305	152,779
Laboratory and other partners
Disaggregation of Revenue [Line Items]
Total revenues	13,701	16,938	42,426	42,093
Patients
Disaggregation of Revenue [Line Items]
Total revenues	6,438	9,170	19,896	24,216
Product
Disaggregation of Revenue [Line Items]
Total revenues	93,286	66,936	260,746	195,399
Licensing and other
Disaggregation of Revenue [Line Items]
Total revenues	$ 4,857	$ 10,973	$ 17,881	$ 23,689