PENSION AND POST-RETIREMENT PLANS - FAIR VALUE (Details) - Pensions - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension and Post-retirement Plans
Total	$ 178.8	$ 168.9	$ 178.9
Significant Unobservable Inputs (Level 3) | Private equity partnership interests
Pension and Post-retirement Plans
Total	0.1	0.2	$ 0.3
Fair Value Measurement
Pension and Post-retirement Plans
Total	178.8	168.9
Fair Value Measurement | Cash
Pension and Post-retirement Plans
Total	7.8	6.9
Fair Value Measurement | U.S. large-cap
Pension and Post-retirement Plans
Total	67.1	64.5
Fair Value Measurement | U.S. mid- and small-cap
Pension and Post-retirement Plans
Total	38.9	34.7
Fair Value Measurement | International large-cap
Pension and Post-retirement Plans
Total	16.9	16.5
Fair Value Measurement | International small-cap
Pension and Post-retirement Plans
Total	6.9	6.1
Fair Value Measurement | U.S. Treasuries
Pension and Post-retirement Plans
Total	8.9	5.6
Fair Value Measurement | Municipal bonds
Pension and Post-retirement Plans
Total	9.3	5.3
Fair Value Measurement | Investment grade U.S. corporate bonds
Pension and Post-retirement Plans
Total	5.3	2.4
Fair Value Measurement | High-yield U.S. corporate bonds
Pension and Post-retirement Plans
Total	6.3	6.0
Fair Value Measurement | Emerging markets fixed income
Pension and Post-retirement Plans
Total	0.5	10.4
Fair Value Measurement | Real estate partnerships interests
Pension and Post-retirement Plans
Total	10.8	10.3
Fair Value Measurement | Private equity partnership interests
Pension and Post-retirement Plans
Total	0.1	0.2
Fair Value Measurement | Quoted Prices in Active Markets (Level 1)
Pension and Post-retirement Plans
Total	71.6	94.6
Fair Value Measurement | Quoted Prices in Active Markets (Level 1) | Cash
Pension and Post-retirement Plans
Total	7.8	6.9
Fair Value Measurement | Quoted Prices in Active Markets (Level 1) | U.S. large-cap
Pension and Post-retirement Plans
Total	31.6	48.6
Fair Value Measurement | Quoted Prices in Active Markets (Level 1) | U.S. mid- and small-cap
Pension and Post-retirement Plans
Total	31.7	28.7
Fair Value Measurement | Quoted Prices in Active Markets (Level 1) | Emerging markets fixed income
Pension and Post-retirement Plans
Total	0.5	10.4
Fair Value Measurement | Significant Observable Inputs (Level 2)
Pension and Post-retirement Plans
Total	96.3	63.8
Fair Value Measurement | Significant Observable Inputs (Level 2) | U.S. large-cap
Pension and Post-retirement Plans
Total	35.5	15.9
Fair Value Measurement | Significant Observable Inputs (Level 2) | U.S. mid- and small-cap
Pension and Post-retirement Plans
Total	7.2	6.0
Fair Value Measurement | Significant Observable Inputs (Level 2) | International large-cap
Pension and Post-retirement Plans
Total	16.9	16.5
Fair Value Measurement | Significant Observable Inputs (Level 2) | International small-cap
Pension and Post-retirement Plans
Total	6.9	6.1
Fair Value Measurement | Significant Observable Inputs (Level 2) | U.S. Treasuries
Pension and Post-retirement Plans
Total	8.9	5.6
Fair Value Measurement | Significant Observable Inputs (Level 2) | Municipal bonds
Pension and Post-retirement Plans
Total	9.3	5.3
Fair Value Measurement | Significant Observable Inputs (Level 2) | Investment grade U.S. corporate bonds
Pension and Post-retirement Plans
Total	5.3	2.4
Fair Value Measurement | Significant Observable Inputs (Level 2) | High-yield U.S. corporate bonds
Pension and Post-retirement Plans
Total	6.3	6.0
Fair Value Measurement | Significant Unobservable Inputs (Level 3)
Pension and Post-retirement Plans
Total	10.9	10.5
Fair Value Measurement | Significant Unobservable Inputs (Level 3) | Real estate partnerships interests
Pension and Post-retirement Plans
Total	10.8	10.3
Fair Value Measurement | Significant Unobservable Inputs (Level 3) | Private equity partnership interests
Pension and Post-retirement Plans
Total	$ 0.1	$ 0.2