RETIREMENT PLANS - Fair Value of Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension | U.S.
Defined Benefit Plan Disclosure
Total	$ 1,981.4	$ 2,226.4	$ 1,950.1
Pension | International
Defined Benefit Plan Disclosure
Total investments at fair value	911.2	966.2
Investments measured at NAV	14.4	14.9
Total	925.6	981.1	$ 821.9
Pension | International | Level 1
Defined Benefit Plan Disclosure
Total investments at fair value	27.3	29.3
Total	27.3	29.3
Pension | International | Level 2
Defined Benefit Plan Disclosure
Total investments at fair value	883.9	936.9
Total	883.9	936.9
Pension | International | Level 3
Defined Benefit Plan Disclosure
Total	0.0	0.0
Pension | International | Cash
Defined Benefit Plan Disclosure
Total investments at fair value	7.1	8.7
Pension | International | Cash | Level 1
Defined Benefit Plan Disclosure
Total investments at fair value	7.1	8.7
Pension | International | International equity
Defined Benefit Plan Disclosure
Total investments at fair value	412.1	442.2
Pension | International | International equity | Level 2
Defined Benefit Plan Disclosure
Total investments at fair value	412.1	442.2
Pension | International | Corporate bonds
Defined Benefit Plan Disclosure
Total investments at fair value	170.0	181.2
Pension | International | Corporate bonds | Level 1
Defined Benefit Plan Disclosure
Total investments at fair value	7.9	8.2
Pension | International | Corporate bonds | Level 2
Defined Benefit Plan Disclosure
Total investments at fair value	162.1	173.0
Pension | International | Government bonds
Defined Benefit Plan Disclosure
Total investments at fair value	181.5	190.0
Pension | International | Government bonds | Level 1
Defined Benefit Plan Disclosure
Total investments at fair value	12.3	12.4
Pension | International | Government bonds | Level 2
Defined Benefit Plan Disclosure
Total investments at fair value	169.2	177.6
Pension | International | Insurance company accounts
Defined Benefit Plan Disclosure
Total investments at fair value	140.5	144.1
Pension | International | Insurance company accounts | Level 2
Defined Benefit Plan Disclosure
Total investments at fair value	140.5	144.1
Pension and Postretirement Health Care Benefit Plans | U.S.
Defined Benefit Plan Disclosure
Total investments at fair value	1,649.8	1,959.5
Total	1,987.4	2,234.0
Pension and Postretirement Health Care Benefit Plans | U.S. | Level 1
Defined Benefit Plan Disclosure
Total investments at fair value	1,649.5	1,959.2
Total	1,649.5	1,959.2
Pension and Postretirement Health Care Benefit Plans | U.S. | Level 2
Defined Benefit Plan Disclosure
Total investments at fair value	0.3	0.3
Total	0.3	0.3
Pension and Postretirement Health Care Benefit Plans | U.S. | Level 3
Defined Benefit Plan Disclosure
Total	0.0	0.0
Pension and Postretirement Health Care Benefit Plans | U.S. | Cash
Defined Benefit Plan Disclosure
Total investments at fair value	7.1	8.0
Pension and Postretirement Health Care Benefit Plans | U.S. | Cash | Level 1
Defined Benefit Plan Disclosure
Total investments at fair value	7.1	8.0
Pension and Postretirement Health Care Benefit Plans | U.S. | Large cap equity
Defined Benefit Plan Disclosure
Total investments at fair value	683.5	869.8
Pension and Postretirement Health Care Benefit Plans | U.S. | Large cap equity | Level 1
Defined Benefit Plan Disclosure
Total investments at fair value	683.5	869.8
Pension and Postretirement Health Care Benefit Plans | U.S. | Small cap equity
Defined Benefit Plan Disclosure
Total investments at fair value	168.6	198.4
Pension and Postretirement Health Care Benefit Plans | U.S. | Small cap equity | Level 1
Defined Benefit Plan Disclosure
Total investments at fair value	168.6	198.4
Pension and Postretirement Health Care Benefit Plans | U.S. | International equity
Defined Benefit Plan Disclosure
Total investments at fair value	285.0	340.2
Investments measured at NAV	337.6	274.5
Pension and Postretirement Health Care Benefit Plans | U.S. | International equity | Level 1
Defined Benefit Plan Disclosure
Total investments at fair value	285.0	340.2
Pension and Postretirement Health Care Benefit Plans | U.S. | Core fixed income
Defined Benefit Plan Disclosure
Total investments at fair value	358.3	390.0
Pension and Postretirement Health Care Benefit Plans | U.S. | Core fixed income | Level 1
Defined Benefit Plan Disclosure
Total investments at fair value	358.3	390.0
Pension and Postretirement Health Care Benefit Plans | U.S. | High-yield bonds
Defined Benefit Plan Disclosure
Total investments at fair value	107.6	109.9
Pension and Postretirement Health Care Benefit Plans | U.S. | High-yield bonds | Level 1
Defined Benefit Plan Disclosure
Total investments at fair value	107.6	109.9
Pension and Postretirement Health Care Benefit Plans | U.S. | Emerging markets
Defined Benefit Plan Disclosure
Total investments at fair value	39.4	42.9
Pension and Postretirement Health Care Benefit Plans | U.S. | Emerging markets | Level 1
Defined Benefit Plan Disclosure
Total investments at fair value	39.4	42.9
Pension and Postretirement Health Care Benefit Plans | U.S. | Insurance company accounts
Defined Benefit Plan Disclosure
Total investments at fair value	0.3	0.3
Pension and Postretirement Health Care Benefit Plans | U.S. | Insurance company accounts | Level 2
Defined Benefit Plan Disclosure
Total investments at fair value	$ 0.3	$ 0.3