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PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Annual Contributions To The Pension Plans) (Details) $ in Millions | 12 Months Ended
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Dec. 31, 2015 USD ($) | Dec. 31, 2014 USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Company contributions |  | $ 3.5 | $ 5.5
Expected company contributions, next fiscal year | [1] | $ 4.1 |
Funded percentage |  | 70.00% |
Value of VEBA Trust Assets as a Percentage of the Funding Obligation |  | 0.9 |
Pension Benefits [Member] |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Company contributions |  | $ 35.7 | 49.6
Expected company contributions, next fiscal year | [1] | 1.2 |
Direct Payments [Member] |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Company contributions |  | 3.5 | 5.5
Expected company contributions, next fiscal year | [1] | 4.1 |
Veba Trust [Member] |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Company contributions |  | 0.0 | $ 0.0
Expected company contributions, next fiscal year | [1] | $ 0.0 |
[1] | Pursuant to the bargaining agreement, benefits can be paid from VEBA trusts that are at least 70 percent funded (all VEBA trusts are over 70 percent funded at December 31, 2015). Funding obligations have been suspended as Hibbing's, UTAC's, Tilden's and Empire's share of the value of their respective trust assets have reached 90 percent of their obligation.

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- Definition The increase in the fair value of plan assets from contributions made by the employer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
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- Definition Amount of employer's best estimate of contributions expected to be paid to the plan during the next fiscal year beginning after the date of the latest statement of financial position. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
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