VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Valuation and qualifying accounts [Roll forward]
Accounts receivable due from third-party payor, retroactive adjustment	$ 17,900	$ 16,900
Net operating loss carryforwards valuation allowance	72,486	329
Tax credit valuation allowance		207
Valuation allowance expense (benefit) from Tax Cuts and Jobs Act			$ (112,355)
Federal and state
Valuation and qualifying accounts [Roll forward]
Net operating loss carryforwards valuation allowance	(60,376)	5,919	294,568
Tax credit valuation allowance	49,800	49,800
Valuation allowance expense (benefit) from Tax Cuts and Jobs Act	222,786	(6,042)
Allowance for Doubtful Accounts
Valuation and qualifying accounts [Roll forward]
Balance at beginning of period	7,941	23,112	27,044
Charged to costs and expenses	15,166	17,597	25,370
Charged to other accounts	4,182	2,779	555
Deductions	(19,476)	(22,288)	(29,857)
Balance at end of period	7,813	7,941	23,112
Deferred Tax Valuation Allowance
Valuation and qualifying accounts [Roll forward]
Balance at beginning of period	336,417	336,087	264,305
Charged to costs and expenses	60,376	330	71,782
Charged to other accounts	13,790	0	0
Deductions	(1,680)	0	0
Balance at end of period	408,903	336,417	336,087
ASU 2014-09
Valuation and qualifying accounts [Roll forward]
Accounts receivable due from third-party payor, retroactive adjustment		13,300
ASU 2014-09 | Allowance for Doubtful Accounts
Valuation and qualifying accounts [Roll forward]
Balance at beginning of period		$ 9,853
Balance at end of period			$ 9,853
ASU 2016-02
Valuation and qualifying accounts [Roll forward]
Net operating loss carryforwards valuation allowance	$ (13,790)