Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	$ 121,340	$ 125,444	$ 358,597	$ 318,451
Clinical Services
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	102,227	108,733	300,119	275,599
Clinical Services | Client direct billing
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	64,195	72,896	188,040	172,431
Clinical Services | Commercial Insurance
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	19,539	19,218	58,642	56,360
Clinical Services | Medicare and Medicaid
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	18,295	16,460	52,929	46,484
Clinical Services | Self-Pay
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	198	159	508	324
Pharma Services
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	$ 19,113	$ 16,711	$ 58,478	$ 42,852