Revenue Recognition and Contractual Adjustments - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	$ 104,672	$ 69,096	$ 301,962	$ 200,266
Clinical Services
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	92,565	59,449	267,757	175,960
Clinical Services | Client direct billing
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	53,555	39,779	155,999	120,925
Clinical Services | Commercial Insurance
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	20,956	10,253	63,052	28,726
Clinical Services | Medicare and Medicaid
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	17,818	8,603	47,961	25,333
Clinical Services | Self-Pay
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	236	814	745	976
Pharma Services
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	$ 12,107	$ 9,647	$ 34,205	$ 24,306