POSTRETIREMENT MEDICAL BENEFITS - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Transition Obligation Amortization Period	20 years
Workers' Compensation Disclosure [Abstract]
Workers' compensation, beginning of year (including current portion)	$ 11,626,000	$ 10,378,000
Accretion	204,000	348,000
Claims paid	(475,000)	(585,000)
Actuarial changes	(1,825,000)	1,485,000
Workers' compensation, end of year	9,530,000	11,626,000
Less current portion	(820,000)	(911,000)
Workers' compensation, less current portion	8,710,000	10,715,000
Workers' compensation discount, percent	2.00%	2.00%
Postretirement Medical Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Prior service costs	(6,356,000)	(6,991,000)
Defined Benefit Plan, Benefit Obligation, Period Increase (Decrease)	75,200,000
Combined Benefit Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Multiemployer Plan, Period Contributions	$ 2,300,000	$ 2,600,000	$ 3,000,000