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EMPLOYEE BENEFIT PLANS (Nonunion Plan Assets - FV) (Details) - Nonunion Defined Benefit Pension Plan - USD ($) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Pension and other postretirement benefit plans |  |  |
Fair value of plan assets | $ 136,917 | $ 158,265 | $ 207,613
Cash and Cash Equivalents |  |  |
Pension and other postretirement benefit plans |  |  |
Fair value of plan assets | 19,079 | 19,085 |
Debt Instruments |  |  |
Pension and other postretirement benefit plans |  |  |
Fair value of plan assets | 26,662 | 32,361 |
Floating Rate Loan Fund |  |  |
Pension and other postretirement benefit plans |  |  |
Fair value of plan assets | 15,868 | 16,106 |
Large Cap U.S. Equity |  |  |
Pension and other postretirement benefit plans |  |  |
Fair value of plan assets | 23,459 | 29,964 |
Mid Cap U.S. Equity |  |  |
Pension and other postretirement benefit plans |  |  |
Fair value of plan assets | 14,276 | 19,180 |
Small Cap U.S. Equity |  |  |
Pension and other postretirement benefit plans |  |  |
Fair value of plan assets | 14,135 | 17,899 |
International Equity |  |  |
Pension and other postretirement benefit plans |  |  |
Fair value of plan assets | 23,438 | 23,670 |
Level 1 |  |  |
Pension and other postretirement benefit plans |  |  |
Fair value of plan assets | 110,255 | 125,904 |
Level 1 | Cash and Cash Equivalents |  |  |
Pension and other postretirement benefit plans |  |  |
Fair value of plan assets | 19,079 | 19,085 |
Level 1 | Floating Rate Loan Fund |  |  |
Pension and other postretirement benefit plans |  |  |
Fair value of plan assets | 15,868 | 16,106 |
Level 1 | Large Cap U.S. Equity |  |  |
Pension and other postretirement benefit plans |  |  |
Fair value of plan assets | 23,459 | 29,964 |
Level 1 | Mid Cap U.S. Equity |  |  |
Pension and other postretirement benefit plans |  |  |
Fair value of plan assets | 14,276 | 19,180 |
Level 1 | Small Cap U.S. Equity |  |  |
Pension and other postretirement benefit plans |  |  |
Fair value of plan assets | 14,135 | 17,899 |
Level 1 | International Equity |  |  |
Pension and other postretirement benefit plans |  |  |
Fair value of plan assets | 23,438 | 23,670 |
Level 2 |  |  |
Pension and other postretirement benefit plans |  |  |
Fair value of plan assets | 26,662 | 32,361 |
Level 2 | Debt Instruments |  |  |
Pension and other postretirement benefit plans |  |  |
Fair value of plan assets | $ 26,662 | $ 32,361 |
Level 2 | Corporate debt securities |  |  |
Pension and other postretirement benefit plans |  |  |
Percentage of investments in debt instruments | 74.00% | 66.00% |
Level 2 | Mortgage-backed instruments |  |  |
Pension and other postretirement benefit plans |  |  |
Percentage of investments in debt instruments | 17.00% | 24.00% |
Level 2 | Treasury instruments |  |  |
Pension and other postretirement benefit plans |  |  |
Percentage of investments in debt instruments | 6.00% | 5.00% |
Level 2 | Municipal debt securities |  |  |
Pension and other postretirement benefit plans |  |  |
Percentage of investments in debt instruments | 2.00% | 4.00% |
Level 2 | Agency securities |  |  |
Pension and other postretirement benefit plans |  |  |
Percentage of investments in debt instruments | 1.00% | 1.00% |

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- Definition Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 30 -Section 35 -Paragraph 50 -URI http://asc.fasb.org/extlink&oid=49178875&loc=d3e12355-114930 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
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