RETIREMENT BENEFIT PLANS - Health care trend rates (Details) $ in Millions	12 Months Ended
Dec. 31, 2020 USD ($)
Effect of one-percentage point change in assumed health care cost trend rates [Abstract]
Effect of one percentage point increase on accumulated postretirement benefit obligation	$ 1
Effect of one percentage point decrease on accumulated postretirement benefit obligation	(1)
Effect of one percentage point increase on service and interest cost components	(1)
Effect of one percentage point decrease on service and interest cost components	$ 1

No definition available.

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- Definition

Amount of decrease in accumulated postretirement benefit obligation from one-percentage-point decrease in assumed health care cost trend rate.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (m)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

+ Details

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- Definition

Amount of decrease in service and interest cost components of net periodic postretirement benefit cost from one-percentage-point decrease in assumed health care cost trend rate.

+ References

+ Details

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- Definition

Amount of increase in accumulated postretirement benefit obligation from one-percentage-point increase in assumed health care cost trend rate.

+ References

+ Details

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- Definition

Amount of increase in service and interest cost components of net periodic postretirement benefit cost from one-percentage-point increase in assumed health care cost trend rate.

+ References

+ Details

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