BENEFIT PLANS (Fair values of Pension Plan Assets) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	$ 816,972		$ 756,624		$ 683,091
Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	816,972		756,624
Pension Plans, Defined Benefit | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	164,695		137,034
Pension Plans, Defined Benefit | Commodity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	19,480		23,773
Pension Plans, Defined Benefit | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	507,369		490,957
Pension Plans, Defined Benefit | Short Term Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	15,495		16,378
Pension Plans, Defined Benefit | Venture Capital And Partnerships [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	109,933		88,482
Fair Value, Inputs, Level 1 | Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	457	[1]	602	[1]
Fair Value, Inputs, Level 1 | Pension Plans, Defined Benefit | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	[1]	0	[1]
Fair Value, Inputs, Level 1 | Pension Plans, Defined Benefit | Commodity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	[1]	0	[1]
Fair Value, Inputs, Level 1 | Pension Plans, Defined Benefit | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	457	[1]	602	[1]
Fair Value, Inputs, Level 1 | Pension Plans, Defined Benefit | Short Term Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	[1]	0	[1]
Fair Value, Inputs, Level 1 | Pension Plans, Defined Benefit | Venture Capital And Partnerships [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	[1]	0	[1]
Fair Value, Inputs, Level 2 | Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	706,582	[1]	667,540	[1]
Fair Value, Inputs, Level 2 | Pension Plans, Defined Benefit | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	164,695	[1]	137,034	[1]
Fair Value, Inputs, Level 2 | Pension Plans, Defined Benefit | Commodity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	19,480	[1]	23,773	[1]
Fair Value, Inputs, Level 2 | Pension Plans, Defined Benefit | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	506,912	[1]	490,355	[1]
Fair Value, Inputs, Level 2 | Pension Plans, Defined Benefit | Short Term Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	15,495	[1]	16,378	[1]
Fair Value, Inputs, Level 2 | Pension Plans, Defined Benefit | Venture Capital And Partnerships [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	[1]	0	[1]
Fair Value, Inputs, Level 3 | Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	109,933	[1]	88,482	[1]
Fair Value, Inputs, Level 3 | Pension Plans, Defined Benefit | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	[1]	0	[1]
Fair Value, Inputs, Level 3 | Pension Plans, Defined Benefit | Commodity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	[1]	0	[1]
Fair Value, Inputs, Level 3 | Pension Plans, Defined Benefit | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	[1]	0	[1]
Fair Value, Inputs, Level 3 | Pension Plans, Defined Benefit | Short Term Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	[1]	0	[1]
Fair Value, Inputs, Level 3 | Pension Plans, Defined Benefit | Venture Capital And Partnerships [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	$ 109,933	[1]	$ 88,482	[1]

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