Segment reporting - Selected Balance Sheet information (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Segment Reporting Information
Assets	$ 74,189,163	$ 65,926,000	$ 65,910,369
Deposits	66,013,561	56,866,340
Puerto Rico
Segment Reporting Information
Assets	62,401,086	54,143,954
Loans	20,097,055	20,413,112
Deposits	56,247,551	47,586,880
Popular U.S.
Segment Reporting Information
Assets	10,900,069	10,878,030
Loans	8,211,160	8,396,983
Deposits	7,836,138	7,672,549
Other
Segment Reporting Information
Assets	888,008	904,016
Loans	638,470	674,556
Deposits	$ 1,929,872	$ 1,606,911