EMPLOYEE BENEFIT PLANS (Details) (USD $)	1 Months Ended	3 Months Ended		9 Months Ended
	Oct. 31, 2013	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
EMPLOYEE BENEFIT PLANS
Service cost - benefits earned during the period		$ 2,708,000	$ 2,561,000	$ 8,124,000	$ 7,683,000
Interest cost on projected benefit obligation		2,553,000	2,604,000	7,659,000	7,812,000
Expected return on plan assets		(2,759,000)	(2,673,000)	(8,277,000)	(8,019,000)
Amortization of prior service cost/(credit)		(95,000)	(95,000)	(285,000)	(285,000)
Amortization of actuarial losses		2,729,000	2,175,000	8,187,000	6,525,000
Total benefit cost		5,136,000	4,572,000	15,408,000	13,716,000
Contribution made by the company to its defined benefit pension plan for the plan year 2012				2,000,000
Contribution made by the company to its defined benefit pension plan for the plan year 2013	$ 2,300,000			$ 4,600,000
Adjusted funding target percentage to be maintained				80.00%
Age of eligibility for prescription drug benefit				65 years