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Goodwill and intangible assets - Additional Information (Details)
12 Months Ended
Dec. 31, 2021
cash_generating_unit
divisions
Dec. 31, 2020
Disclosure of detailed information about intangible assets [line items]    
Number of cash generating units | cash_generating_unit 11  
Number of divisions included in cash generating units | divisions 3  
Projection period 5 years  
Bottom of range    
Disclosure of detailed information about intangible assets [line items]    
Pre-tax discount rate 6.40% 6.00%
Top of range    
Disclosure of detailed information about intangible assets [line items]    
Amortisation period of finite-life intangible assets ten years  
Pre-tax discount rate 7.60% 7.40%