EMPLOYEE BENEFIT PLANS (Details) (USD $)	3 Months Ended		1 Months Ended	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Apr. 30, 2014 Defined Benefit Pension Plan	Mar. 31, 2014 Defined Benefit Pension Plan	Mar. 31, 2014 Defined Benefit Pension Plan Minimum	Mar. 31, 2014 Retiree medical plan Minimum
EMPLOYEE BENEFIT PLANS
Service cost - benefits earned during the period	$ 2,453,000	$ 2,708,000
Interest cost on projected benefit obligation	2,993,000	2,553,000
Expected return on plan assets	(3,065,000)	(2,759,000)
Amortization of prior service cost/(credit)	(95,000)	(95,000)
Amortization of actuarial losses	1,897,000	2,729,000
Total benefit cost	4,183,000	5,136,000
EMPLOYEE BENEFIT PLANS
Contribution made by the company to its defined benefit pension plan for the plan year 2013				2,300,000
Contribution made by the company to its defined benefit pension plan for the plan year 2014			$ 3,100,000
Adjusted funding target percentage to be maintained					80.00%
Age of eligibility for prescription drug benefit						65 years