PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Estimated Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions  | 
3 Months Ended | |
|---|---|---|
Mar. 31, 2018  | 
Mar. 31, 2017  | 
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| Pension Plan [Member] | ||
| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] | ||
| Service cost | $ 4.7 | $ 4.8 | 
| Interest cost | 7.6 | 7.5 | 
| Expected return on plan assets | (15.0) | (13.5) | 
| Prior service credits | 0.5 | 0.6 | 
| Net actuarial loss | 5.3 | 5.3 | 
| Net periodic benefit credit | 3.1 | 4.7 | 
| Other Postretirement Benefit Plans, Defined Benefit [Member] | ||
| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] | ||
| Service cost | 0.5 | 0.5 | 
| Interest cost | 2.1 | 2.1 | 
| Expected return on plan assets | (4.6) | (4.4) | 
| Prior service credits | (0.8) | (0.7) | 
| Net actuarial loss | 1.2 | 1.2 | 
| Net periodic benefit credit | $ (1.6) | $ (1.3) | 
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- Definition Amount of gain (loss) recognized in net periodic benefit (cost) credit of defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Amount of prior service cost (credit) recognized in net periodic benefit cost (credit) of defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Amount of expected return (loss) recognized in net periodic benefit (cost) credit, calculated based on expected long-term rate of return and market-related value of plan assets of defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Amount of cost recognized for passage of time related to defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Amount of net periodic benefit cost (credit) for defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available. 
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