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PENSIONS AND OTHER POST-EMPLOYMENT BENEFIT OBLIGATIONS - Narrative (Details) - EUR (€) € in Millions | 12 Months Ended
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Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Disclosure of defined benefit plans [line items] |  |  |  |
Gains on pension plan amendments | € (32) | € (2) | € 1 |
Weighted-average maturity of defined benefit obligations | 14 years 2 months 12 days | 14 years 2 months 12 days |  |
Other Benefits |  |  |  |
Disclosure of defined benefit plans [line items] |  |  |  |
Gains on pension plan amendments |  |  |  | € 36
Expected contributions to pension and other benefits for next year | € 18 |  |  |
OPEB |  |  |  |
Disclosure of defined benefit plans [line items] |  |  |  |
Loss recognized on disputes about plan changes | 31 |  |  |
Pension Benefits |  |  |  |
Disclosure of defined benefit plans [line items] |  |  |  |
Expected contributions to pension and other benefits for next year | € 22 |  |  |
Actuarial assumption of discount rates |  |  |  |
Disclosure of defined benefit plans [line items] |  |  |  |
Increase in actuarial assumption | 0.50% |  |  |

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- Definition The estimate of the expected contributions to be made to a defined benefit plan for the next annual reporting period. [Refer: Defined benefit plans [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2021-01-01 -Paragraph 147 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_147_b&doctype=Standard -URIDate 2021-03-24 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2021-01-01 -Paragraph 148 -Subparagraph d -Clause iii -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_148_d_iii&doctype=Standard -URIDate 2021-03-24 + Details
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- Definition The reasonably possible percentage of the increase in the actuarial assumption used to determine the present value of defined benefit obligation. [Refer: Actuarial assumptions [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2021-01-01 -Paragraph 145 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_145_a&doctype=Standard -URIDate 2021-03-24 + Details
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