Segment information - Summary of Disaggregation of sales by markets (Detail) - EUR (€) € in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation Of Sales By Markets [Line Items]
Revenue	€ 50,724	€ 51,980	€ 50,982
Emerging markets [Member]
Disaggregation Of Sales By Markets [Line Items]
Revenue	29,281	31,021	29,654
Developed markets [Member]
Disaggregation Of Sales By Markets [Line Items]
Revenue	€ 21,443	€ 20,959	€ 21,328

The income arising in the course of an entity's ordinary activities. Income is increases in assets, or decreases in liabilities, that result in increases in equity, other than those relating to contributions from holders of equity claims.

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+ Details