| ACCUMULATED OTHER COMPREHENSIVE INCOME - Reclassifications Out Of Accumulated Other Comprehensive Income (Details) $ in Millions | 3 Months Ended | |||
|---|---|---|---|---|
| Mar. 31, 2017  USD ($) | ||||
| Prior service cost | ||||
| Amortization of pension and other postretirement plan items: | ||||
| Total net periodic benefit cost, before tax | $ 0.1 | [1] | ||
| Recognized actuarial loss | ||||
| Amortization of pension and other postretirement plan items: | ||||
| Total net periodic benefit cost, before tax | (4.2) | [1] | ||
| Accumulated Defined Benefit Plans Adjustment Attributable to Parent | ||||
| Amortization of pension and other postretirement plan items: | ||||
| Total net periodic benefit cost, before tax | (4.1) | |||
| Total net periodic benefit cost, tax benefit | 1.6 | |||
| Total net periodic benefit cost, net of tax | $ (2.5) | |||
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- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. No definition available. 
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- Definition Amount before tax of reclassification adjustments of other comprehensive income (loss). Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Amount after tax of reclassification adjustments of other comprehensive income (loss). Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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- Definition Amount of tax expense (benefit) of reclassification adjustment from accumulated other comprehensive income (loss). Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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