Earnings per share (Details) - GBP (£) £ / shares in Units, £ in Millions, shares in Millions	6 Months Ended
Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021
Earnings per share [abstract]
Profit attributable to ordinary shareholders	£ 2,569	£ 1,744	£ 3,611
Weighted-average number of ordinary shares in issue – basic (in shares)	70,192	70,979	70,894
Adjustment for share options and awards (in shares)	881	842	854
Weighted-average number of ordinary shares in issue – diluted (in shares)	71,073	71,821	71,748
Basic earnings per share (in GBP per share)	£ 0.037	£ 0.024	£ 0.051
Diluted earnings per share (in GBP per share)	£ 0.036	£ 0.024	£ 0.050

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).

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

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The profit (loss) attributable to ordinary equity holders of the parent entity. [Refer: Profit (loss)]

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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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