PENSION AND POST-RETIREMENT BENEFITS - Fair Value of Asset Categories (Details) - USD ($) $ in Millions | Dec. 31, 2018 | Dec. 31, 2017 |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | $ 432.4 | $ 497.2 |
Level 1, 2 and 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 360.6 | 410.9 |
Level 1 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 159.7 | 194.8 |
Level 2 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 200.9 | 216.1 |
Level 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Investments measured at Net Asset Value | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 71.8 | 86.3 |
Common and preferred stock | Level 1, 2 and 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 7 | 18.3 |
Common and preferred stock | Level 1 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 7 | 18.3 |
Common and preferred stock | Level 2 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Common and preferred stock | Level 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Mutual Funds, Corporate Bonds | Level 1, 2 and 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 10.6 | 17.7 |
Mutual Funds, Corporate Bonds | Level 1 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 10.6 | 17.7 |
Mutual Funds, Corporate Bonds | Level 2 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Mutual Funds, Corporate Bonds | Level 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Mutual Funds, Government Bonds | Level 1, 2 and 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 13.4 | 8.4 |
Mutual Funds, Government Bonds | Level 1 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 13.4 | 8.4 |
Mutual Funds, Government Bonds | Level 2 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Mutual Funds, Government Bonds | Level 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Mutual Funds, U.S. Large Cap Equiy | Level 1, 2 and 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0.2 | 0.1 |
Mutual Funds, U.S. Large Cap Equiy | Level 1 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0.2 | 0.1 |
Mutual Funds, U.S. Large Cap Equiy | Level 2 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Mutual Funds, U.S. Large Cap Equiy | Level 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Mutual Funds, International Equities | Level 1, 2 and 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 9.4 | 3.8 |
Mutual Funds, International Equities | Level 1 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 9.4 | 3.8 |
Mutual Funds, International Equities | Level 2 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Mutual Funds, International Equities | Level 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Mutual Funds, Emerging Markets International Equity | Level 1, 2 and 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 5.3 | 7.4 |
Mutual Funds, Emerging Markets International Equity | Level 1 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 5.3 | 7.4 |
Mutual Funds, Emerging Markets International Equity | Level 2 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Mutual Funds, Emerging Markets International Equity | Level 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Mutual Funds, Cash and Cash Equivalents | Level 1, 2 and 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 2.2 | |
Mutual Funds, Cash and Cash Equivalents | Level 1 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 2.2 | |
Mutual Funds, Cash and Cash Equivalents | Level 2 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | |
Mutual Funds, Cash and Cash Equivalents | Level 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | |
Mutual Funds, Other | Level 1, 2 and 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 1.8 | 4.5 |
Mutual Funds, Other | Level 1 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 1.8 | 4.5 |
Mutual Funds, Other | Level 2 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Mutual Funds, Other | Level 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Fixed Income Securities, Corporate Bonds | Level 1, 2 and 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | | 46.7 |
Fixed Income Securities, Corporate Bonds | Level 1 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | | 0 |
Fixed Income Securities, Corporate Bonds | Level 2 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | | 46.7 |
Fixed Income Securities, Corporate Bonds | Level 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | | 0 |
Fixed Income Securities, Government Bonds | Level 1, 2 and 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 70 | 15.4 |
Fixed Income Securities, Government Bonds | Level 1 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Fixed Income Securities, Government Bonds | Level 2 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 70 | 15.4 |
Fixed Income Securities, Government Bonds | Level 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Common and Collective Funds, Corporate Bonds | Level 1, 2 and 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 40.7 | 49.8 |
Common and Collective Funds, Corporate Bonds | Level 1 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 19.6 | 27.3 |
Common and Collective Funds, Corporate Bonds | Level 2 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 21.1 | 22.5 |
Common and Collective Funds, Corporate Bonds | Level 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Common and Collective Funds, Government Bonds | Level 1, 2 and 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 43 | 44.1 |
Common and Collective Funds, Government Bonds | Level 1 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 6.6 | 7.4 |
Common and Collective Funds, Government Bonds | Level 2 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 36.4 | 36.7 |
Common and Collective Funds, Government Bonds | Level 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Common and Collective Funds, U.S. Large Cap Equity | Level 1, 2 and 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 54.5 | 68.7 |
Common and Collective Funds, U.S. Large Cap Equity | Level 1 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 38.8 | 55.1 |
Common and Collective Funds, U.S. Large Cap Equity | Level 2 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 15.7 | 13.6 |
Common and Collective Funds, U.S. Large Cap Equity | Level 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Common and Collective Funds, U.S. Small/Mid Cap Equity | Level 1, 2 and 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 6.9 | 16.1 |
Common and Collective Funds, U.S. Small/Mid Cap Equity | Level 1 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 6.9 | 16.1 |
Common and Collective Funds, U.S. Small/Mid Cap Equity | Level 2 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Common and Collective Funds, U.S. Small/Mid Cap Equity | Level 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Common and Collective Funds, International Equities | Level 1, 2 and 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 58.4 | 75.7 |
Common and Collective Funds, International Equities | Level 1 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 5.5 | 5.7 |
Common and Collective Funds, International Equities | Level 2 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 52.9 | 70 |
Common and Collective Funds, International Equities | Level 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Common and Collective Funds, Emerging Markets International Equity | Level 1, 2 and 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 14.9 | 18.3 |
Common and Collective Funds, Emerging Markets International Equity | Level 1 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 8.5 | 10.6 |
Common and Collective Funds, Emerging Markets International Equity | Level 2 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 6.4 | 7.7 |
Common and Collective Funds, Emerging Markets International Equity | Level 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Common and Collective Funds, Cash and Cash Equivalents | Level 1, 2 and 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 1.7 | 4.2 |
Common and Collective Funds, Cash and Cash Equivalents | Level 1 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 1.7 | 4.2 |
Common and Collective Funds, Cash and Cash Equivalents | Level 2 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Common and Collective Funds, Cash and Cash Equivalents | Level 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Common and Collective Funds, Other | Level 1, 2 and 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | (1.6) | 3.5 |
Common and Collective Funds, Other | Level 1 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Common and Collective Funds, Other | Level 2 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | (1.6) | 3.5 |
Common and Collective Funds, Other | Level 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Cash and other investments | Level 1, 2 and 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 22.2 | 8.2 |
Cash and other investments | Level 1 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 22.2 | 8.2 |
Cash and other investments | Level 2 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Cash and other investments | Level 3 | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 0 | 0 |
Common and collective funds | Investments measured at Net Asset Value | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | 36.3 | 37.5 |
Hedge funds | Investments measured at Net Asset Value | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair value of plan assets | $ 35.5 | $ 48.8 |