RETIREMENT BENEFITS - Interest Crediting Rate (Details)	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
U.S.
Defined Benefit Plans and Other Postretirement Benefit Plans
Weighted average interest crediting rate	1.45%	2.25%	3.25%
Non-U.S.
Defined Benefit Plans and Other Postretirement Benefit Plans
Weighted average interest crediting rate	1.60%	1.61%	1.68%

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