Commitments and contingencies - Commitments - Additional Information (Details) - USD ($) $ in Thousands		6 Months Ended	12 Months Ended
	Jul. 02, 2023	Jun. 30, 2023	Dec. 31, 2022
Commitments and Contingencies Disclosure [Line Items]
Loans And Leases Receivable Gross Carrying Amount		$ 33,354,999	$ 32,372,925
Commitments to extend credit
Commitments and Contingencies Disclosure [Line Items]
Reserve of potential losses associated with unfunded loan commitments		11,600	8,800
Noncredit commitment
Commitments and Contingencies Disclosure [Line Items]
Investments		4,800	4,800
Residential mortgage loans
Commitments and Contingencies Disclosure [Line Items]
Loans And Leases Receivable Gross Carrying Amount		1,600,000	1,600,000
Paycheck Protection Program
Commitments and Contingencies Disclosure [Line Items]
Loans And Leases Receivable Gross Carrying Amount		12,000	38,000
BVI | Retail and commerical loans
Commitments and Contingencies Disclosure [Line Items]
Loans And Leases Receivable Gross Carrying Amount		207,000	214,000
PR government and its instrumentalities and municipalities | Loans | Subsequent event | Obligations from Puerto Rico municipalities
Commitments and Contingencies Disclosure [Line Items]
Principal payments received	$ 34,000
Insured or guaranteed by the U.S. Government or its agencies | Commercial Loans
Commitments and Contingencies Disclosure [Line Items]
Loans And Leases Receivable Gross Carrying Amount		71,000	72,000
PR Government direct exposure
Commitments and Contingencies Disclosure [Line Items]
Outstanding concentration of risk		351,483	327,000
Total concentration of risk		$ 380,483	374,000
Exposure Municipal Loans And Securities		74.00%
PR Government direct exposure | Loans
Commitments and Contingencies Disclosure [Line Items]
Outstanding concentration of risk		$ 325,405	302,000
PR Government direct exposure | Securities Investment
Commitments and Contingencies Disclosure [Line Items]
Outstanding concentration of risk		26,078	25,000
PR Government Indirect Exposure
Commitments and Contingencies Disclosure [Line Items]
Outstanding concentration of risk		240,000	251,000
Loans and Leases Receivable, Consumer, Mortgage with PRHA		199,000	209,000
PR Government Indirect Exposure | PR Housing Bonds backed by second mortgage loans
Commitments and Contingencies Disclosure [Line Items]
Outstanding concentration of risk		40,000	42,000
USVI Government Direct Exposure | From USVI Government And Public Corporations
Commitments and Contingencies Disclosure [Line Items]
Total concentration of risk		$ 28,000	$ 28,000