Income taxes - Reconciliation between statutory tax and effective tax charge (Details) - EUR (€) € in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Taxes
Profit (loss) before taxation	€ 10,685	€ (5,978)	€ 5,746
Tax rate (IRES) (%)	24.00%	24.00%	24.00%
Statutory corporation tax charge (credit) on profit or loss	€ 2,564	€ (1,435)	€ 1,379
Increase (decrease) resulting from:
- higher tax charges related to subsidiaries outside Italy	2,301	1,980	2,934
- effect of the valuation of the investments under the equity method	180	97	9
- Italian regional income tax (IRAP)	140	107	25
- effect additional tax law no 7/2009	97
- impact pursuant to foreign tax effects of italian entities	108	108	105
- tax effects related to previous years	52	(30)	147
- effect due to the tax regime provided for intercompany dividends	54	96	65
- impact pursuant to the write-down of deferred tax assets	(666)	1,785	938
- other adjustments	15	(58)	(11)
Net tax effect	2,281	4,085	4,212
Income tax expense	4,845	2,650	5,591
Exploration & Production
Increase (decrease) resulting from:
- higher tax charges related to subsidiaries outside Italy	€ 2,040	€ 1,777	€ 2,934

Disclosure of Income Tax Explanatory.

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Amount of impact pursuant to foreign tax effects of italian entities.

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Increase Decrease Tax Expense Income At Applicable Tax Rate [Abstract]

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Net tax effects during the period for reconciliation between accounting profit and tax expense (income)

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The amount that represents the difference between the tax expense (income) and the product of the accounting profit multiplied by the applicable tax rate(s) that relates to the tax regime provided for intercompany dividends.

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The amount that represents the difference between the tax expense (income) and the product of the accounting profit multiplied by the applicable tax rate(s) that relates to regional income tax.

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Tax effect of valuation of investments under equity method.

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The applicable income tax rate.

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The aggregate amount included in the determination of profit (loss) for the period in respect of current tax and deferred tax. [Refer: Current tax expense (income); Deferred tax expense (income)]

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The amount that represents the difference between the tax expense (income) and the product of the accounting profit multiplied by the applicable tax rate(s) that the entity does not separately disclose in the same statement or note. [Refer: Accounting profit; Applicable tax rate]

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The profit (loss) before tax expense or income. [Refer: Profit (loss)]

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The amount that represents the difference between the tax expense (income) and the product of the accounting profit multiplied by the applicable tax rate(s) that relates to foreign tax rates. [Refer: Accounting profit]

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The product of the accounting profit multiplied by the applicable tax rate(s). [Refer: Accounting profit; Applicable tax rate]

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