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PENSIONS AND OTHER POST-EMPLOYMENT BENEFIT OBLIGATIONS - Additional Information (Details) - EUR (€) € in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Benefits
Disclosure of defined benefit plans [line items]
Gain recognized on negative past service costs	€ 2	€ 3	€ 36

X

- Definition

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

+ References

No definition available.

+ Details

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- Definition

The increase (decrease) in the net defined benefit liability (asset) resulting from past service cost. Past service cost is the change in the present value of the defined benefit obligation for employee service in prior periods, resulting from a plan amendment (the introduction or withdrawal of, or changes to, a defined benefit plan) or a curtailment (a significant reduction by the entity in the number of employees covered by a plan). [Refer: Net defined benefit liability (asset); Defined benefit plans [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 19
-IssueDate 2019-01-01
-Paragraph 141
-Subparagraph d
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2019-en-r&anchor=para_141_d&doctype=Standard
-URIDate 2019-03-27

+ Details

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Period Type:	duration

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- Details

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