CONTINGENCIES AND COMMITMENTS (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Loss Contingencies [Line Items]
Asset Retirement Obligation	$ 7,000,000
Surety Bond Outstanding	52,900,000
Loss Contingency, Damages Sought, Value		$ 1,000,000,000
Standby Letters Of Credit [Member]
Loss Contingencies [Line Items]
Letters of Credit Outstanding, Amount	37,300,000	54,300,000
Financial Standby Letter of Credit [Member]
Loss Contingencies [Line Items]
Letters of Credit Outstanding, Amount	14,700,000	$ 20,700,000
Failure to Meet Contractual Obligations [Member]
Loss Contingencies [Line Items]
Loss Contingency, Damages Sought, Value	25,000,000
Loss Contingency, Range of Possible Loss, Minimum	0
Loss Contingency, Range of Possible Loss, Maximum	$ 48,000,000