Due to banks and correspondents - Loan received from foreign entities (Parenthetical) (Detail) - Due To Foreign Entities [Member]	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Daily Secured Overnight Financing Rate Sofr Overnight Index Swap Rate [Member]
Disclosure Of Dues To Banks And Correspondents [Line Items]
Borrowing Effective Annual Interest Rate	1.30%	1.30%
Bottom of range [member] \| Secured Overnight Financing Rate [member]
Disclosure Of Dues To Banks And Correspondents [Line Items]
Borrowing Effective Annual Interest Rate	4.43%	5.16%
Bottom of range [member] \| Six Month Term Secured Overnight Financing Rate Sofr Overnight Index Swap Rate [Member]
Disclosure Of Dues To Banks And Correspondents [Line Items]
Borrowing Effective Annual Interest Rate	0.55%	0.60%
Bottom of range [member] \| Three Month Term Secured Overnight Financing Rate Sofr Overnight Index Swap Rate [Member]
Disclosure Of Dues To Banks And Correspondents [Line Items]
Borrowing Effective Annual Interest Rate	0.50%	0.70%
Top of range [member] \| Secured Overnight Financing Rate [member]
Disclosure Of Dues To Banks And Correspondents [Line Items]
Borrowing Effective Annual Interest Rate	7.51%	7.51%
Top of range [member] \| Six Month Term Secured Overnight Financing Rate Sofr Overnight Index Swap Rate [Member]
Disclosure Of Dues To Banks And Correspondents [Line Items]
Borrowing Effective Annual Interest Rate	1.70%	1.99%
Top of range [member] \| Three Month Term Secured Overnight Financing Rate Sofr Overnight Index Swap Rate [Member]
Disclosure Of Dues To Banks And Correspondents [Line Items]
Borrowing Effective Annual Interest Rate	1.30%	1.90%