Transfers of financial assets and servicing assets - Key economic assumptions used (Details) - Residential Mortgage	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
BPPR
Assumption for Fair Value as of Balance Sheet Date of Assets or Liabilities that relate to Transferor's Continuing Involvement
Prepayment speed	5.90%	7.20%	7.40%	6.50%
Weighted average life	8 years 10 months 24 days	8 years 9 months 18 days	8 years	9 years 3 months 18 days
Discount rate (annual rate)	10.40%	10.80%	10.50%	10.80%
PB
Assumption for Fair Value as of Balance Sheet Date of Assets or Liabilities that relate to Transferor's Continuing Involvement
Prepayment speed	12.50%	22.70%	21.20%	22.70%
Weighted average life	6 years	3 years 6 months	9 years 6 months	3 years 6 months
Discount rate (annual rate)	11.00%	9.50%	11.00%	9.50%