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Capital Management, Corporate Governance Transparency Policy and Risk Management - Summary of Banks's Shareholders (Detail)
 12 Months Ended
Dec. 31, 2020
Trust "Trust JHB" [member]  
Disclosure of ownership structure of shareholders [line items]  
Participating Interest 17.28%
Voting Interest 19.65%
Carballo Delfin Jorge Ezequiel [member]  
Disclosure of ownership structure of shareholders [line items]  
Participating Interest 17.47%
Voting Interest 19.19%
ANSES FGS Law No. 26425 [member]  
Disclosure of ownership structure of shareholders [line items]  
Participating Interest 28.80%
Voting Interest 26.90%
Grouped shareholders (Local Stock Exchanges) [member]  
Disclosure of ownership structure of shareholders [line items]  
Participating Interest 9.72%
Voting Interest 9.28%
Grouped shareholders (Foreign stock exchanges) [member]  
Disclosure of ownership structure of shareholders [line items]  
Participating Interest 26.73%
Voting Interest 24.98%