Loans - Amortized cost basis and interest income recognized on non-accrual loans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Financing receivable nonaccrual status
Non-accrual with no allowance	$ 299,298		$ 203,460
Non-accrual with allowance	398,844		534,314
Interest income recognized	4,000	$ 3,000
Construction
Financing receivable nonaccrual status
Non-accrual with no allowance	22,400		0
Non-accrual with allowance	0		29,057
Mortgages
Financing receivable nonaccrual status
Non-accrual with no allowance	160,605		142,254
Non-accrual with allowance	244,969		286,953
Commercial | Commercial multi-family
Financing receivable nonaccrual status
Non-accrual with no allowance	0		0
Non-accrual with allowance	814		2,399
Commercial | CRE non-owner occupied
Financing receivable nonaccrual status
Non-accrual with no allowance	60,727		35,968
Non-accrual with allowance	16,189		41,838
Commercial | CRE owner occupied
Financing receivable nonaccrual status
Non-accrual with no allowance	25,612		14,825
Non-accrual with allowance	64,463		77,510
Commercial | Commercial and Industrial
Financing receivable nonaccrual status
Non-accrual with no allowance	22,264		1,148
Non-accrual with allowance	12,701		36,392
Leasing
Financing receivable nonaccrual status
Non-accrual with no allowance	0		0
Non-accrual with allowance	3,040		3,441
Consumer | Home equity lines of credit
Financing receivable nonaccrual status
Non-accrual with no allowance	0		0
Non-accrual with allowance	6,855		7,491
Consumer | Personal loans
Financing receivable nonaccrual status
Non-accrual with no allowance	7,690		9,265
Non-accrual with allowance	19,127		18,596
Consumer | Auto Loan
Financing receivable nonaccrual status
Non-accrual with no allowance	0		0
Non-accrual with allowance	15,405		15,736
Consumer | Other
Financing receivable nonaccrual status
Non-accrual with no allowance	0		0
Non-accrual with allowance	15,281		14,901
Puerto Rico
Financing receivable nonaccrual status
Non-accrual with no allowance	291,775		202,943
Non-accrual with allowance	374,203		497,434
Puerto Rico | Construction
Financing receivable nonaccrual status
Non-accrual with no allowance	14,877		0
Non-accrual with allowance	0		21,497
Puerto Rico | Mortgages
Financing receivable nonaccrual status
Non-accrual with no allowance	160,605		141,737
Non-accrual with allowance	230,176		272,606
Puerto Rico | Commercial | Commercial multi-family
Financing receivable nonaccrual status
Non-accrual with no allowance	0		0
Non-accrual with allowance	814		505
Puerto Rico | Commercial | CRE non-owner occupied
Financing receivable nonaccrual status
Non-accrual with no allowance	60,727		35,968
Non-accrual with allowance	15,797		41,169
Puerto Rico | Commercial | CRE owner occupied
Financing receivable nonaccrual status
Non-accrual with no allowance	25,612		14,825
Non-accrual with allowance	64,140		77,176
Puerto Rico | Commercial | Commercial and Industrial
Financing receivable nonaccrual status
Non-accrual with no allowance	22,264		1,148
Non-accrual with allowance	11,509		33,301
Puerto Rico | Leasing
Financing receivable nonaccrual status
Non-accrual with no allowance	0		0
Non-accrual with allowance	3,040		3,441
Puerto Rico | Consumer | Home equity lines of credit
Financing receivable nonaccrual status
Non-accrual with no allowance	0		0
Non-accrual with allowance	0		0
Puerto Rico | Consumer | Personal loans
Financing receivable nonaccrual status
Non-accrual with no allowance	7,690		9,265
Non-accrual with allowance	18,041		17,122
Puerto Rico | Consumer | Auto Loan
Financing receivable nonaccrual status
Non-accrual with no allowance	0		0
Non-accrual with allowance	15,405		15,736
Puerto Rico | Consumer | Other
Financing receivable nonaccrual status
Non-accrual with no allowance	0		0
Non-accrual with allowance	15,281		14,881
Popular U.S.
Financing receivable nonaccrual status
Non-accrual with no allowance	7,523		517
Non-accrual with allowance	24,641		36,880
Popular U.S. | Construction
Financing receivable nonaccrual status
Non-accrual with no allowance	7,523		0
Non-accrual with allowance	0		7,560
Popular U.S. | Mortgages
Financing receivable nonaccrual status
Non-accrual with no allowance	0		517
Non-accrual with allowance	14,793		14,347
Popular U.S. | Commercial | Commercial multi-family
Financing receivable nonaccrual status
Non-accrual with no allowance	0		0
Non-accrual with allowance	0		1,894
Popular U.S. | Commercial | CRE non-owner occupied
Financing receivable nonaccrual status
Non-accrual with no allowance	0		0
Non-accrual with allowance	392		669
Popular U.S. | Commercial | CRE owner occupied
Financing receivable nonaccrual status
Non-accrual with no allowance	0		0
Non-accrual with allowance	323		334
Popular U.S. | Commercial | Commercial and Industrial
Financing receivable nonaccrual status
Non-accrual with no allowance	0		0
Non-accrual with allowance	1,192		3,091
Popular U.S. | Leasing
Financing receivable nonaccrual status
Non-accrual with no allowance	0		0
Non-accrual with allowance	0		0
Popular U.S. | Consumer | Home equity lines of credit
Financing receivable nonaccrual status
Non-accrual with no allowance	0		0
Non-accrual with allowance	6,855		7,491
Popular U.S. | Consumer | Personal loans
Financing receivable nonaccrual status
Non-accrual with no allowance	0		0
Non-accrual with allowance	1,086		1,474
Popular U.S. | Consumer | Auto Loan
Financing receivable nonaccrual status
Non-accrual with no allowance	0		0
Non-accrual with allowance	0		0
Popular U.S. | Consumer | Other
Financing receivable nonaccrual status
Non-accrual with no allowance	0		0
Non-accrual with allowance	$ 0		$ 20