RETIREMENT PLANS (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Pension plan defined benefit plan cost increase limit percentage			4.00%
Pension Benefits [Member]
Components of net periodic benefit cost [Abstract]
Service cost	$ 3,351,000	$ 3,673,000	$ 10,053,000	$ 11,020,000
Interest cost	3,531,000	3,327,000	10,594,000	9,983,000
Expected return on plan assets	(4,202,000)	(4,481,000)	(12,606,000)	(13,449,000)
Amortization of actuarial (gain) loss	1,372,000	1,932,000	4,115,000	5,799,000
Net periodic benefit cost	4,052,000	4,451,000	12,156,000	13,353,000
Pension Benefits [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan of asset contributions to pension plan obligations	25,000,000		25,000,000
SERP [Member]
Components of net periodic benefit cost [Abstract]
Service cost	0	0	0	0
Interest cost	16,000	16,000	49,000	48,000
Expected return on plan assets	0	0	0	0
Amortization of actuarial (gain) loss	7,000	7,000	20,000	21,000
Net periodic benefit cost	23,000	23,000	69,000	69,000
Other Postretirement Benefits [Member]
Components of net periodic benefit cost [Abstract]
Service cost	0	0	0	0
Interest cost	7,000	9,000	22,000	27,000
Amortization of actuarial (gain) loss	(186,000)	(199,000)	(560,000)	(594,000)
Net periodic benefit cost	$ (179,000)	$ (190,000)	$ (538,000)	$ (567,000)