Related party transactions - Summary of aggregate amounts Payable to Key Management Personnel (Details) - EUR (€) € in Millions	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Related Party [Abstract]
Aggregate top-up pension obligation in favor of certain corporate officers and of Executive Committee members	€ 10	€ 28	€ 32
Aggregate termination benefits and lump-sum retirement benefits in favor of key management personnel	€ 5	€ 7	€ 5

Aggregate pension obligation in favor of certain corporate officers and of members of the executive committee.

No definition available.

Name:	sny_AggregatePensionObligationInFavorOfCertainCorporateOfficersAndOfMembersOfTheExecutiveCommittee
Namespace Prefix:	sny_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration