RETIREMENT PLANS (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Future contributions annual cost limitation, maximum (in hundredths)	4.00%
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Estimated future contribution in current year	$ 5,000,000
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	3,171,000	2,566,000
Interest cost	2,835,000	2,584,000
Expected return on plan assets	(4,027,000)	(3,220,000)
Amortization of actuarial loss	2,056,000	1,752,000
Net periodic benefit cost	4,035,000	3,682,000
SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0
Interest cost	17,000	18,000
Expected return on plan assets	0	0
Amortization of actuarial loss	5,000	4,000
Net periodic benefit cost	22,000	22,000
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0
Interest cost	28,000	33,000
Amortization of actuarial loss	(155,000)	(154,000)
Net periodic benefit cost	$ (127,000)	$ (121,000)