RETIREMENT PLANS - Assumption Details (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
United States | Corporate bonds | Minimum
Weighted-average actuarial assumptions used to determine net cost:
Maturity period of debt securities			6 months
United States | Corporate bonds | Maximum
Weighted-average actuarial assumptions used to determine net cost:
Maturity period of debt securities			30 years
United States | Pension
Weighted-average actuarial assumptions used to determine benefit obligations as of year end:
Discount rate (as a percent)	4.34%		2.48%	3.20%	4.34%
Projected salary increase (as a percent)	4.03%		4.03%	4.03%	4.03%
Weighted-average actuarial assumptions used to determine net cost:
Interest credit rate for cash balance plans			1.81%
Discount rate (as a percent)			3.20%	4.34%	3.70%
Expected return on plan assets (as a percent)			7.25%	7.25%	7.75%
Projected salary increase (as a percent)			4.03%	4.03%	4.03%
Defined Benefit Plan Assumed Health Care Cost Trend Rates
Plan amendments, decrease in benefit obligation	$ (40.4)
United States | Postretirement Health Care
Weighted-average actuarial assumptions used to determine benefit obligations as of year end:
Discount rate (as a percent)	4.29%	4.36%	2.37%	3.16%	4.29%
Weighted-average actuarial assumptions used to determine net cost:
Discount rate (as a percent)			3.16%	4.29%	3.66%
Expected return on plan assets (as a percent)			7.25%	7.25%	7.75%
Defined Benefit Plan Assumed Health Care Cost Trend Rates
Annual rates of increase in the per capita cost of covered health care for pre-age 65 retirees (as a percent)			8.00%
Annual rates of increase in the per capita cost of covered health care for post-age 65 retirees (as a percent)			10.75%
Rate of per capita cost of covered health care, in 2028 (as a percent)			5.00%
Plan amendments, decrease in benefit obligation		$ (18.9)
Plan amendments, decrease in benefit obligation, net of tax		$ (14.4)
Defined Benefit Plan, Reduction in Benefit Cost					$ (4.5)
International | Pension
Weighted-average actuarial assumptions used to determine benefit obligations as of year end:
Discount rate (as a percent)	2.49%		1.13%	1.52%	2.49%
Projected salary increase (as a percent)	2.46%		2.12%	2.50%	2.46%
Weighted-average actuarial assumptions used to determine net cost:
Discount rate (as a percent)			1.84%	2.66%	2.29%
Expected return on plan assets (as a percent)			6.24%	6.66%	6.67%
Projected salary increase (as a percent)			2.81%	2.70%	2.67%
Defined Benefit Plan Assumed Health Care Cost Trend Rates
Plan amendments, decrease in benefit obligation			$ (1.7)	$ 0.1