Revenue Recognition - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Total revenues	$ 222,451	$ 254,914
Services
Disaggregation of Revenue [Line Items]
Total revenues	178,891	211,315
Healthcare insurers
Disaggregation of Revenue [Line Items]
Total revenues	105,878	132,253
Government payers
Disaggregation of Revenue [Line Items]
Total revenues	29,510	35,190
Client payers
Disaggregation of Revenue [Line Items]
Total revenues	38,422	38,032
Patients
Disaggregation of Revenue [Line Items]
Total revenues	$ 5,081	$ 5,840