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PENSIONS AND OTHER POST-EMPLOYMENT BENEFIT OBLIGATIONS - Amounts Recognized in the Consolidated Income Statement (Details) - EUR (€) € in Millions | 3 Months Ended | 6 Months Ended | 12 Months Ended
--- | --- | --- | ---
Jun. 30, 2021 | Jun. 30, 2020 | Jun. 30, 2021 | Jun. 30, 2020 | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Disclosure of defined benefit plans [line items] |  |  |  |  |  |  |
Current service cost | € (8) | € (6) | € (15) | € (14) |  |  |
Past service cost | (2) | (2) | (2) | (2) |  |  |
Net interest | (2) | (3) | (4) | (6) |  |  |
Immediate recognition of gains arising over the year | 0 | (1) | 1 | 0 |  |  |
Administration expenses | 0 | (1) | (1) | (1) |  |  |
Total | (12) | (13) | (21) | (23) |  |  |
Pension Benefits |  |  |  |  |  |  |
Disclosure of defined benefit plans [line items] |  |  |  |  |  |  |
Current service cost | (6) | (5) | (11) | (11) |  |  |
Past service cost | 0 | 0 | 0 | 0 |  |  |
Net interest | (1) | (2) | (2) | (3) |  |  |
Immediate recognition of gains arising over the year | 0 | 0 | 0 | 0 |  |  |
Administration expenses | 0 | (1) | (1) | (1) |  |  |
Total | (7) | (8) | (14) | (15) |  |  |
Other Benefits |  |  |  |  |  |  |
Disclosure of defined benefit plans [line items] |  |  |  |  |  |  |
Current service cost | (2) | (1) | (4) | (3) |  |  |
Past service cost | (2) | (2) | (2) | (2) | € (2) | € (3) | € 36
Net interest | (1) | (1) | (2) | (3) |  |  |
Immediate recognition of gains arising over the year | 0 | (1) | 1 | 0 |  |  |
Administration expenses | 0 | 0 | 0 | 0 |  |  |
Total | € (5) | € (5) | € (7) | € (8) |  |  |

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- Definition Immediate recognition actuarial gains (losses) arising from change in assumption recognized in profit (loss). + References No definition available. + Details
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- Definition The amount of expenses that the entity classifies as being administrative. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 26 -IssueDate 2020-01-01 -Paragraph 35 -Subparagraph b -Clause vi -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=26&code=ifrs-tx-2020-en-r&anchor=para_35_b_vi&doctype=Standard -URIDate 2020-01-01 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Name IAS -Number 1 -IssueDate 2020-01-01 -Paragraph 103 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_103&doctype=Standard -URIDate 2020-01-01 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2020-01-01 -Paragraph 99 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_99&doctype=Standard -URIDate 2020-01-01 + 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 2020-01-01 -Paragraph 141 -Subparagraph d -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2020-en-r&anchor=para_141_d&doctype=Standard -URIDate 2020-01-01 + Details
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