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EMPLOYEE BENEFIT PLANS (Nonunion Plan Assets) (Details) - Nonunion Defined Benefit Pension Plan | 12 Months Ended |
--- | --- | ---
Dec. 31, 2016 | Dec. 31, 2015
Nonunion Defined Benefit Pension, Supplemental Benefit, and Postretirement Health Benefit Plans |  |
Expected return on plan assets expected to be utilized in determining pension plan expenses for next fiscal year (as a percent) | 6.50% |
Period over which the possibility of experiencing a substantial loss is limited by adequate diversification under the long-term asset allocation policy | 1 year |
Target allocations, acceptable ranges, and actual asset allocations |  |
Target allocation (as a percent) | 100.00% |
Weighted-Average Allocation (as a percent) | 100.00% | 100.00%
Maximum performance period of investment fund used to compare investment performance | 3 years |
Minimum performance period of total fund used to compare investment performance | 5 years |
Minimum |  |
Target allocations, acceptable ranges, and actual asset allocations |  |
Performance period of recognized market indices used to compare investment performance | 3 years |
Maximum |  |
Target allocations, acceptable ranges, and actual asset allocations |  |
Performance period of recognized market indices used to compare investment performance | 5 years |
Large Cap U.S. Equity |  |
Target allocations, acceptable ranges, and actual asset allocations |  |
Target allocation (as a percent) | 13.00% |
Acceptable Range, minimum (as a percent) | 8.00% |
Acceptable Range, maximum (as a percent) | 20.00% |
Weighted-Average Allocation (as a percent) | 14.00% | 17.20%
Mid Cap U.S. Equity |  |
Target allocations, acceptable ranges, and actual asset allocations |  |
Target allocation (as a percent) | 9.00% |
Acceptable Range, minimum (as a percent) | 7.00% |
Acceptable Range, maximum (as a percent) | 11.00% |
Weighted-Average Allocation (as a percent) | 9.40% | 10.40%
Small Cap U.S. Equity |  |
Target allocations, acceptable ranges, and actual asset allocations |  |
Target allocation (as a percent) | 9.00% |
Acceptable Range, minimum (as a percent) | 7.00% |
Acceptable Range, maximum (as a percent) | 11.00% |
Weighted-Average Allocation (as a percent) | 10.00% | 10.30%
International Equity |  |
Target allocations, acceptable ranges, and actual asset allocations |  |
Target allocation (as a percent) | 14.00% |
Acceptable Range, minimum (as a percent) | 10.00% |
Acceptable Range, maximum (as a percent) | 18.00% |
Weighted-Average Allocation (as a percent) | 14.40% | 17.10%
Debt Instruments |  |
Target allocations, acceptable ranges, and actual asset allocations |  |
Target allocation (as a percent) | 25.00% |
Acceptable Range, minimum (as a percent) | 20.00% |
Acceptable Range, maximum (as a percent) | 30.00% |
Weighted-Average Allocation (as a percent) | 25.00% | 19.50%
Actively managed portfolio of short-term debt instruments | Minimum |  |
Target allocations, acceptable ranges, and actual asset allocations |  |
Maturity period of investments | 1 year |
Actively managed portfolio of short-term debt instruments | Maximum |  |
Target allocations, acceptable ranges, and actual asset allocations |  |
Maturity period of investments | 5 years |
Actively managed portfolio of short-duration debt instruments | Minimum |  |
Target allocations, acceptable ranges, and actual asset allocations |  |
Maturity period of investments | 1 year |
Actively managed portfolio of short-duration debt instruments | Maximum |  |
Target allocations, acceptable ranges, and actual asset allocations |  |
Maturity period of investments | 3 years |
Floating Rate Loan Fund |  |
Target allocations, acceptable ranges, and actual asset allocations |  |
Target allocation (as a percent) | 10.00% |
Acceptable Range, minimum (as a percent) | 3.00% |
Acceptable Range, maximum (as a percent) | 15.00% |
Weighted-Average Allocation (as a percent) | 10.80% | 11.60%
Cash and Cash Equivalents |  |
Target allocations, acceptable ranges, and actual asset allocations |  |
Target allocation (as a percent) | 20.00% |
Acceptable Range, minimum (as a percent) | 0.00% |
Acceptable Range, maximum (as a percent) | 25.00% |
Weighted-Average Allocation (as a percent) | 16.40% | 13.90%

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