Revenue Recognition and Contractual Adjustments - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	$ 125,444	$ 104,672	$ 318,451	$ 301,962
Clinical Services
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	108,733	92,565	275,599	267,757
Clinical Services | Client direct billing
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	72,896	53,555	172,431	155,999
Clinical Services | Commercial Insurance
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	19,218	20,956	56,360	63,052
Clinical Services | Medicare and Medicaid
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	16,460	17,818	46,484	47,961
Clinical Services | Self-Pay
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	159	236	324	745
Pharma Services
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	$ 16,711	$ 12,107	$ 42,852	$ 34,205