Revenue Recognition and Contractual Adjustments - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	$ 106,030	$ 95,577
Clinical Services
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	92,982	86,210
Clinical Services | Client direct billing
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	54,292	49,756
Clinical Services | Commercial Insurance
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	21,993	20,433
Clinical Services | Medicare and Medicaid
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	16,483	15,793
Clinical Services | Self-Pay
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	214	228
Pharma Services
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	$ 13,048	$ 9,367