INCOME TAXES - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
State operating loss carryforwards, valuation allowance	$ 9,500,000	$ 9,600,000
Unfavorable change in valuation allowance, before federal income taxes	100,000
Loss carryforwards	658,400,000	581,300,000
Loss carryforward, subject to expiration	27,600,000	54,800,000
Loss carryforward, not subject to expiration	630,800,000	526,500,000
Unrecognized tax benefits with high certainty of deductibility but with uncertainty about the timing of deductions	0	0
Amount of unrecognized tax benefits that would affect the effective income tax rate if recognized	1,800,000	1,800,000	$ 7,100,000
Accrued interest related to the unrecognized tax benefits included in income tax expense	0	$ 0	$ 0
State jurisdiction
Operating Loss Carryforwards [Line Items]
Deferred tax asset, operating loss carryforwards	$ 9,100,000