Shareholder remuneration and earnings per share - EPS Diluted (Details) - EUR (€) € / shares in Units, € in Millions	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017
Diluted earnings per share [abstract]
Profit (loss), attributable to owners of parent	€ 3,752	€ 3,616
Remuneration of contingently convertible preference shares (CCP) (millions of euros)	(266)	(178)
Profit attributable to ordinary equity holders of parent including dilutive effects	3,486	3,438
Profit or Loss from continuing operations (net of non-controlling interests and CCP) (millions of euros)	€ 3,486	€ 3,438
Weighted average number of shares outstanding	16,129,055,793	14,823,034,696
Dilutive effect of options/rights on shares	45,858,082	44,860,827
Adjusted number of shares	16,174,913,875	14,867,895,523
Total diluted earnings (loss) per share	€ 0.220	€ 0.230
Diluted earnings per share from continuing operations (euros)	€ 0.220	€ 0.230

The weighted average number of ordinary shares outstanding plus the weighted average number of ordinary shares that would be issued on the conversion of all the dilutive potential ordinary shares into ordinary shares. [Refer: Ordinary shares [member]; Weighted average [member]]

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The amount of profit (loss) attributable to ordinary equity holders of the parent entity (the numerator), divided by the weighted average number of ordinary shares outstanding during the period (the denominator), both adjusted for the effects of all dilutive potential ordinary shares. [Refer: Ordinary shares [member]; Weighted average [member]]

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Diluted earnings (loss) per share from continuing operations. [Refer: Continuing operations [member]; Diluted earnings (loss) per share]

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The increase (decrease) in equity resulting from the conversion of convertible instruments.

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The profit (loss) attributable to ordinary equity holders of the parent equity, adjusted for the effects of all dilutive potential ordinary shares. [Refer: Profit (loss)]

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The profit (loss) attributable to owners of the parent. [Refer: Profit (loss)]

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The profit (loss) from continuing operations attributable to ordinary equity holders of the parent equity, adjusted for the effects of all dilutive potential ordinary shares. [Refer: Profit (loss) from continuing operations]

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The number of ordinary shares outstanding at the beginning of the period, adjusted by the number of ordinary shares bought back or issued during the period multiplied by a time-weighting factor.

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The number of dilutive potential ordinary shares that relate to the assumed exercise of the entity's share options and the effect of share rights.

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