Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenue	$ 106,868	$ 104,672	$ 101,713	$ 95,577	$ 76,475	$ 69,097	$ 67,746	$ 63,423	$ 408,830	$ 276,741	$ 240,251
Clinical Services
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenue									361,161	241,873	213,097
Pharma Services
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenue									47,669	34,868	27,154
Client direct billing | Clinical Services
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenue									212,703	164,888	147,726
Commercial Insurance | Clinical Services
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenue									83,107	40,360	35,473
Medicare and Medicaid | Clinical Services
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenue									64,745	35,566	29,493
Self-Pay | Clinical Services
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenue									$ 606	$ 1,059	$ 405