INCOME TAXES - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards, subject to expiration	$ 8,000
Federal net operating losses and other carryforwards	46,000
Reclassification between income tax receivable and deferred tax assets	6,800
Additional alternative minimum tax	13,000
Tax Cuts And Jobs Act Of 2017, deferred tax assets, tax credit carryforward, alternative minimum tax, receivable, net	75,700
Tax Cuts And Jobs Act Of 2017, deferred tax assets, tax credit carryforward, alternative minimum tax, noncurrent receivable, estimate for sequestration rate reduction	5,000
State operating loss carryforwards and other tax carryforwards portion about to expire	301,000
Deferred tax assets, valuation allowance	7,700
Tax Cuts And Jobs Act Of 2017, incomplete accounting, change in tax rate, deferred tax liability, provisional income tax benefit	247,800
Tax Cuts And Jobs Act Of 2017, incomplete accounting, change in tax rate, change in deferred tax assets valuation allowance, amount	2,000
Tax Cuts And Jobs Act Of 2017, incomplete accounting, change in tax rate, deferred tax asset, provisional income tax expense	400
Impact of state deferred tax revaluation on San Juan properties	0	$ 153	$ 1,241
Unrecognized tax benefits that would impact effective tax rate	4,200
Income tax interest expense (income) net of tax benefit and penalties	31	101	$ 2
Accrued interest (net of tax benefit) and penalties payments	300	$ 300
2015
Operating Loss Carryforwards [Line Items]
Federal net operating loss carrybacks, subject to expiration	$ 38,000