CONTINGENCIES AND COMMITMENTS (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Loss Contingencies [Line Items]
Asset Retirement Obligation	$ 7,800,000
Surety Bond Outstanding	45,600,000
Standby letters of credit
Loss Contingencies [Line Items]
Letters of credit	21,100,000	$ 32,600,000
Financial Standby Letter of Credit [Member]
Loss Contingencies [Line Items]
Letters of credit	5,600,000	$ 10,800,000
Failure to Meet Contractual Obligations [Member]
Loss Contingencies [Line Items]
Loss Contingency, Damages Sought, Value	25,000,000
Minimum | Failure to Meet Contractual Obligations [Member]
Loss Contingencies [Line Items]
Loss Contingency, Range of Possible Loss	0
Maximum | Failure to Meet Contractual Obligations [Member]
Loss Contingencies [Line Items]
Loss Contingency, Range of Possible Loss	$ 55,500,000