ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Accrued compensation and benefits:
Accrued compensation	$ 20,299	$ 24,526
Accrued vacation pay	17,438	12,670
Accrued compensation and benefits	37,737	37,196
Accrued expenses and other current liabilities:
Refunds due to payors	28,166	20,085
Deferred revenue - advanced payments from CMS	83,193	0
Grant funds escrow	16,758	0
Accrued settlement	12,714	6,573
IPO put liability	16,685	0
Other	16,098	10,935
Accrued expenses and other current liabilities	$ 173,614	$ 37,593