Segment reporting - Selected Balance Sheet information (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Segment Reporting Information
Total assets	$ 65,910,369	$ 52,115,324	$ 52,480,415
Deposits	56,021,983	43,758,606
Puerto Rico
Segment Reporting Information
Total assets	54,218,254	40,544,255
Loans	20,548,257	18,989,286
Deposits	46,831,116	34,664,243
Popular U.S.
Segment Reporting Information
Total assets	10,797,883	10,693,536
Loans	8,276,731	7,819,187
Deposits	7,662,877	7,664,792
Other
Segment Reporting Information
Total assets	894,232	877,533
Loans	670,282	657,603
Deposits	$ 1,527,990	$ 1,429,571