Transfers of financial assets and servicing assets - Key economic assumptions used (Details) - Residential Mortgage	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
BPPR
Assumption for Fair Value as of Balance Sheet Date of Assets or Liabilities that relate to Transferor's Continuing Involvement [Line Items]
Prepayment speed	7.30%	5.50%	7.10%	5.20%
Weighted average life	9 years 2 months 12 days	9 years 6 months	9 years 2 months 12 days	9 years 8 months 12 days
Discount rate (annual rate)	9.60%	10.70%	9.60%	10.50%
PB
Assumption for Fair Value as of Balance Sheet Date of Assets or Liabilities that relate to Transferor's Continuing Involvement [Line Items]
Prepayment speed	7.00%	7.20%	7.10%	8.40%
Weighted average life	8 years	8 years 2 months 12 days	8 years	7 years 8 months 12 days
Discount rate (annual rate)	11.00%	10.00%	10.70%	9.80%