BENEFIT PLANS (Fair values of Pension Plan Assets) (Details) - USD ($) $ in Thousands		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets		$ 745,686	$ 816,972	$ 756,624
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets		745,686	816,972
Pension Plans, Defined Benefit [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets		154,745	164,695
Pension Plans, Defined Benefit [Member] | Commodity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets		14,490	19,480
Pension Plans, Defined Benefit [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets		464,063	507,369
Pension Plans, Defined Benefit [Member] | Short Term Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets		9,516	15,495
Pension Plans, Defined Benefit [Member] | Venture Capital And Partnerships [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets		102,872	109,933
Level 1 [Member] | Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[1]	647	457
Level 1 [Member] | Pension Plans, Defined Benefit [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[1]	0	0
Level 1 [Member] | Pension Plans, Defined Benefit [Member] | Commodity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[1]	0	0
Level 1 [Member] | Pension Plans, Defined Benefit [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[1]	647	457
Level 1 [Member] | Pension Plans, Defined Benefit [Member] | Short Term Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[1]	0	0
Level 1 [Member] | Pension Plans, Defined Benefit [Member] | Venture Capital And Partnerships [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[1]	0	0
Level 2 [Member] | Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[1]	642,167	706,582
Level 2 [Member] | Pension Plans, Defined Benefit [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[1]	154,745	164,695
Level 2 [Member] | Pension Plans, Defined Benefit [Member] | Commodity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[1]	14,490	19,480
Level 2 [Member] | Pension Plans, Defined Benefit [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[1]	463,416	506,912
Level 2 [Member] | Pension Plans, Defined Benefit [Member] | Short Term Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[1]	9,516	15,495
Level 2 [Member] | Pension Plans, Defined Benefit [Member] | Venture Capital And Partnerships [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[1]	0	0
Level 3 [Member] | Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[1]	102,872	109,933
Level 3 [Member] | Pension Plans, Defined Benefit [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[1]	0	0
Level 3 [Member] | Pension Plans, Defined Benefit [Member] | Commodity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[1]	0	0
Level 3 [Member] | Pension Plans, Defined Benefit [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[1]	0	0
Level 3 [Member] | Pension Plans, Defined Benefit [Member] | Short Term Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[1]	0	0
Level 3 [Member] | Pension Plans, Defined Benefit [Member] | Venture Capital And Partnerships [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[1]	$ 102,872	$ 109,933

[1] See Note 1 under the caption Fair Value Measurements for a description of the fair value hierarchy.