Loans - Amortized cost basis of collateral dependent loans by class (Details) $ in Thousands	Mar. 31, 2020 USD ($)
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	$ 27,662,272
Collateral assets
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	585,322
Real Estate
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	555,975
Auto
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	1,736
Equipment
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	4
Taxi medallions
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	4,430
Accounts receivable
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	13,612
Other
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	9,565
Construction
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	902,380
Mortgages
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	7,094,757
Mortgages | Collateral assets
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	196,500
Mortgages | Real Estate
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	196,500
Mortgages | Auto
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Mortgages | Equipment
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Mortgages | Taxi medallions
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Mortgages | Accounts receivable
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Mortgages | Other
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Commercial | Commercial multi-family
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	1,777,610
Commercial | Commercial multi-family | Collateral assets
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	2,097
Commercial | Commercial multi-family | Real Estate
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	2,097
Commercial | Commercial multi-family | Auto
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Commercial | Commercial multi-family | Equipment
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Commercial | Commercial multi-family | Taxi medallions
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Commercial | Commercial multi-family | Accounts receivable
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Commercial | Commercial multi-family | Other
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Commercial | CRE non-owner occupied
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	4,063,723
Commercial | CRE non-owner occupied | Collateral assets
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	291,083
Commercial | CRE non-owner occupied | Real Estate
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	291,083
Commercial | CRE non-owner occupied | Auto
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Commercial | CRE non-owner occupied | Equipment
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Commercial | CRE non-owner occupied | Taxi medallions
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Commercial | CRE non-owner occupied | Accounts receivable
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Commercial | CRE non-owner occupied | Other
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Commercial | CRE owner occupied
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	1,921,371
Commercial | CRE owner occupied | Collateral assets
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	62,330
Commercial | CRE owner occupied | Real Estate
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	62,330
Commercial | CRE owner occupied | Auto
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Commercial | CRE owner occupied | Equipment
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Commercial | CRE owner occupied | Taxi medallions
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Commercial | CRE owner occupied | Accounts receivable
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Commercial | CRE owner occupied | Other
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Commercial | Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	4,736,265
Commercial | Commercial and Industrial | Collateral assets
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	31,572
Commercial | Commercial and Industrial | Real Estate
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	3,965
Commercial | Commercial and Industrial | Auto
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Commercial | Commercial and Industrial | Equipment
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Commercial | Commercial and Industrial | Taxi medallions
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	4,430
Commercial | Commercial and Industrial | Accounts receivable
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	13,612
Commercial | Commercial and Industrial | Other
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	9,565
Leasing
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	1,088,542
Leasing | Collateral assets
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	191
Leasing | Real Estate
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Leasing | Auto
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	187
Leasing | Equipment
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	4
Leasing | Taxi medallions
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Leasing | Accounts receivable
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Leasing | Other
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Consumer | Credit cards
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	1,064,723
Consumer | Home equity lines of credit
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	122,340
Consumer | Personal loans
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	1,778,214
Consumer | Auto Loan
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	2,954,150
Consumer | Auto Loan | Collateral assets
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	1,549
Consumer | Auto Loan | Real Estate
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Consumer | Auto Loan | Auto
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	1,549
Consumer | Auto Loan | Equipment
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Consumer | Auto Loan | Taxi medallions
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Consumer | Auto Loan | Accounts receivable
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Consumer | Auto Loan | Other
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Consumer | Other
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	137,762
Puerto Rico
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	20,223,881
Puerto Rico | Collateral assets
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	578,078
Puerto Rico | Real Estate
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	553,161
Puerto Rico | Auto
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	1,736
Puerto Rico | Equipment
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	4
Puerto Rico | Taxi medallions
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Puerto Rico | Accounts receivable
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	13,612
Puerto Rico | Other
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	9,565
Puerto Rico | Construction
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	164,390
Puerto Rico | Mortgages
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	6,016,008
Puerto Rico | Mortgages | Collateral assets
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	195,783
Puerto Rico | Mortgages | Real Estate
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	195,783
Puerto Rico | Mortgages | Auto
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Puerto Rico | Mortgages | Equipment
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Puerto Rico | Mortgages | Taxi medallions
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Puerto Rico | Mortgages | Accounts receivable
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Puerto Rico | Mortgages | Other
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Puerto Rico | Commercial | Commercial multi-family
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	147,265
Puerto Rico | Commercial | CRE non-owner occupied
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	2,086,899
Puerto Rico | Commercial | CRE non-owner occupied | Collateral assets
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	291,083
Puerto Rico | Commercial | CRE non-owner occupied | Real Estate
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	291,083
Puerto Rico | Commercial | CRE non-owner occupied | Auto
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Puerto Rico | Commercial | CRE non-owner occupied | Equipment
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Puerto Rico | Commercial | CRE non-owner occupied | Taxi medallions
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Puerto Rico | Commercial | CRE non-owner occupied | Accounts receivable
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Puerto Rico | Commercial | CRE non-owner occupied | Other
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Puerto Rico | Commercial | CRE owner occupied
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	1,578,411
Puerto Rico | Commercial | CRE owner occupied | Collateral assets
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	62,330
Puerto Rico | Commercial | CRE owner occupied | Real Estate
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	62,330
Puerto Rico | Commercial | CRE owner occupied | Auto
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Puerto Rico | Commercial | CRE owner occupied | Equipment
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Puerto Rico | Commercial | CRE owner occupied | Taxi medallions
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Puerto Rico | Commercial | CRE owner occupied | Accounts receivable
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Puerto Rico | Commercial | CRE owner occupied | Other
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Puerto Rico | Commercial | Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	3,518,407
Puerto Rico | Commercial | Commercial and Industrial | Collateral assets
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	27,142
Puerto Rico | Commercial | Commercial and Industrial | Real Estate
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	3,965
Puerto Rico | Commercial | Commercial and Industrial | Auto
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Puerto Rico | Commercial | Commercial and Industrial | Equipment
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Puerto Rico | Commercial | Commercial and Industrial | Taxi medallions
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Puerto Rico | Commercial | Commercial and Industrial | Accounts receivable
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	13,612
Puerto Rico | Commercial | Commercial and Industrial | Other
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	9,565
Puerto Rico | Leasing
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	1,088,542
Puerto Rico | Leasing | Collateral assets
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	191
Puerto Rico | Leasing | Real Estate
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Puerto Rico | Leasing | Auto
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	187
Puerto Rico | Leasing | Equipment
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	4
Puerto Rico | Leasing | Taxi medallions
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Puerto Rico | Leasing | Accounts receivable
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Puerto Rico | Leasing | Other
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Puerto Rico | Consumer | Credit cards
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	1,064,687
Puerto Rico | Consumer | Home equity lines of credit
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	4,929
Puerto Rico | Consumer | Personal loans
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	1,463,226
Puerto Rico | Consumer | Auto Loan
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	2,954,150
Puerto Rico | Consumer | Auto Loan | Collateral assets
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	1,549
Puerto Rico | Consumer | Auto Loan | Real Estate
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Puerto Rico | Consumer | Auto Loan | Auto
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	1,549
Puerto Rico | Consumer | Auto Loan | Equipment
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Puerto Rico | Consumer | Auto Loan | Taxi medallions
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Puerto Rico | Consumer | Auto Loan | Accounts receivable
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Puerto Rico | Consumer | Auto Loan | Other
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Puerto Rico | Consumer | Other
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	136,967
Popular U.S.
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	7,438,391
Popular U.S. | Collateral assets
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	7,244
Popular U.S. | Real Estate
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	2,814
Popular U.S. | Auto
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Popular U.S. | Equipment
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Popular U.S. | Taxi medallions
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	4,430
Popular U.S. | Accounts receivable
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Popular U.S. | Other
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Popular U.S. | Construction
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	737,990
Popular U.S. | Mortgages
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	1,078,749
Popular U.S. | Mortgages | Collateral assets
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	717
Popular U.S. | Mortgages | Real Estate
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	717
Popular U.S. | Mortgages | Auto
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Popular U.S. | Mortgages | Equipment
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Popular U.S. | Mortgages | Taxi medallions
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Popular U.S. | Mortgages | Accounts receivable
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Popular U.S. | Mortgages | Other
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Popular U.S. | Commercial | Commercial multi-family
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	1,630,345
Popular U.S. | Commercial | Commercial multi-family | Collateral assets
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	2,097
Popular U.S. | Commercial | Commercial multi-family | Real Estate
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	2,097
Popular U.S. | Commercial | Commercial multi-family | Auto
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Popular U.S. | Commercial | Commercial multi-family | Equipment
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Popular U.S. | Commercial | Commercial multi-family | Taxi medallions
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Popular U.S. | Commercial | Commercial multi-family | Accounts receivable
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Popular U.S. | Commercial | Commercial multi-family | Other
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Popular U.S. | Commercial | CRE non-owner occupied
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	1,976,824
Popular U.S. | Commercial | CRE owner occupied
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	342,960
Popular U.S. | Commercial | Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	1,217,858
Popular U.S. | Commercial | Commercial and Industrial | Collateral assets
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	4,430
Popular U.S. | Commercial | Commercial and Industrial | Real Estate
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Popular U.S. | Commercial | Commercial and Industrial | Auto
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Popular U.S. | Commercial | Commercial and Industrial | Equipment
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Popular U.S. | Commercial | Commercial and Industrial | Taxi medallions
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	4,430
Popular U.S. | Commercial | Commercial and Industrial | Accounts receivable
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Popular U.S. | Commercial | Commercial and Industrial | Other
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	0
Popular U.S. | Consumer | Credit cards
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	36
Popular U.S. | Consumer | Home equity lines of credit
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	117,411
Popular U.S. | Consumer | Personal loans
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	314,988
Popular U.S. | Consumer | Other
Accounts, Notes, Loans and Financing Receivable
Notes Receivable Gross	$ 795