Segment reporting - Selected Balance Sheet information (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Segment Reporting Information
Assets	$ 66,870,268	$ 65,926,000	$ 52,803,639
Total deposits	58,742,801	56,866,340
Puerto Rico
Segment Reporting Information
Assets	54,832,769	54,143,954
Loans	20,226,682	20,413,112
Total deposits	49,133,585	47,586,880
Popular U.S.
Segment Reporting Information
Assets	11,128,729	10,878,030
Loans	8,315,116	8,396,983
Total deposits	7,987,426	7,672,549
Other
Segment Reporting Information
Assets	908,770	904,016
Loans	674,044	674,556
Total deposits	$ 1,621,790	$ 1,606,911