REVENUE - Net Revenue Earned by Category of Payer (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Net revenue	$ 740,848	$ 497,266	$ 1,446,288	$ 973,758
Commercial payers
Disaggregation of Revenue [Line Items]
Net revenue	642,726	439,747	1,248,720	847,554
Government payers
Disaggregation of Revenue [Line Items]
Net revenue	95,124	52,062	181,395	114,595
Patients
Disaggregation of Revenue [Line Items]
Net revenue	$ 2,998	$ 5,457	$ 16,173	$ 11,609