BENEFIT PLANS (Fair values of Pension Plan Assets) (Details) - Pension Benefits [Member] - USD ($) $ in Thousands		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets		$ 749,515	$ 745,686	$ 816,972
Interest In Common/Collective Trusts [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[1]	358,345	349,854
Venture Capital And Partnerships [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[1]	86,745	102,872
Investments In The Fair Value Hierarchy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets		304,425	292,960
Investments In The Fair Value Hierarchy [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets		162,894	154,745
Investments In The Fair Value Hierarchy [Member] | Commodity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets		16,594	14,490
Investments In The Fair Value Hierarchy [Member] | Equities Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets		124,937	123,725
Investments In The Fair Value Hierarchy [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[2]	530	647
Investments In The Fair Value Hierarchy [Member] | Level 1 [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[2]	0	0
Investments In The Fair Value Hierarchy [Member] | Level 1 [Member] | Commodity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[2]	0	0
Investments In The Fair Value Hierarchy [Member] | Level 1 [Member] | Equities Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[2]	530	647
Investments In The Fair Value Hierarchy [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[2]	303,895	292,313
Investments In The Fair Value Hierarchy [Member] | Level 2 [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[2]	162,894	154,745
Investments In The Fair Value Hierarchy [Member] | Level 2 [Member] | Commodity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[2]	16,594	14,490
Investments In The Fair Value Hierarchy [Member] | Level 2 [Member] | Equities Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[2]	124,407	123,078
Investments In The Fair Value Hierarchy [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[2]	0	0
Investments In The Fair Value Hierarchy [Member] | Level 3 [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[2]	0	0
Investments In The Fair Value Hierarchy [Member] | Level 3 [Member] | Commodity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[2]	0	0
Investments In The Fair Value Hierarchy [Member] | Level 3 [Member] | Equities Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	[2]	$ 0	$ 0

[1] As discussed in Note 1, we adopted ASU 2015-07 as of March 31, 2016. As a result, pension plan assets measured using the net asset value practical expedient were excluded from the fair value hierarchy.

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