ESTIMATION OF FAIR VALUE - Trading assets in debt securities pledged as collateral (Details) - Financial assets at fair value through profit or loss, classified as held for trading, category, International Financial Reporting Standards 9 [member] - COP ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Debt securities [member]
Disclosure of financial assets [line items]
Financial assets pledged as collateral	$ 2,853,286	$ 2,000,025
Pledged in money market operations | Debt securities [member]
Disclosure of financial assets [line items]
Financial assets pledged as collateral	2,774,296	1,946,580
Pledged in money market operations | Securities issued or secured by Colombian Government
Disclosure of financial assets [line items]
Financial assets pledged as collateral	2,702,953	1,940,594
Pledged in money market operations | Securities issued or secured by other Colombian Government entities
Disclosure of financial assets [line items]
Financial assets pledged as collateral		1,006
Pledged in money market operations | Securities issued or secured by other financial entities
Disclosure of financial assets [line items]
Financial assets pledged as collateral	71,343	4,980
Pledged as collateral to special entities such as CRCC, BR and BVC | Debt securities [member]
Disclosure of financial assets [line items]
Financial assets pledged as collateral	78,990	52,153
Pledged as collateral to special entities such as CRCC, BR and BVC | Securities issued or secured by Colombian Government
Disclosure of financial assets [line items]
Financial assets pledged as collateral	78,990	52,153
Pledged as collateral in operations with derivative instruments | Debt securities [member]
Disclosure of financial assets [line items]
Financial assets pledged as collateral		1,292
Pledged as collateral in operations with derivative instruments | Securities issued or secured by Colombian Government
Disclosure of financial assets [line items]
Financial assets pledged as collateral		1,292
Level 1 of fair value hierarchy [member] | Debt securities [member]
Disclosure of financial assets [line items]
Financial assets pledged as collateral	2,781,943	1,856,741
Level 1 of fair value hierarchy [member] | Pledged in money market operations | Debt securities [member]
Disclosure of financial assets [line items]
Financial assets pledged as collateral	2,702,953	1,803,296
Level 1 of fair value hierarchy [member] | Pledged in money market operations | Securities issued or secured by Colombian Government
Disclosure of financial assets [line items]
Financial assets pledged as collateral	2,702,953	1,803,296
Level 1 of fair value hierarchy [member] | Pledged as collateral to special entities such as CRCC, BR and BVC | Debt securities [member]
Disclosure of financial assets [line items]
Financial assets pledged as collateral	78,990	52,153
Level 1 of fair value hierarchy [member] | Pledged as collateral to special entities such as CRCC, BR and BVC | Securities issued or secured by Colombian Government
Disclosure of financial assets [line items]
Financial assets pledged as collateral	78,990	52,153
Level 1 of fair value hierarchy [member] | Pledged as collateral in operations with derivative instruments | Debt securities [member]
Disclosure of financial assets [line items]
Financial assets pledged as collateral		1,292
Level 1 of fair value hierarchy [member] | Pledged as collateral in operations with derivative instruments | Securities issued or secured by Colombian Government
Disclosure of financial assets [line items]
Financial assets pledged as collateral		1,292
Level 2 of fair value hierarchy [member] | Debt securities [member]
Disclosure of financial assets [line items]
Financial assets pledged as collateral	71,343	143,284
Level 2 of fair value hierarchy [member] | Pledged in money market operations | Debt securities [member]
Disclosure of financial assets [line items]
Financial assets pledged as collateral	71,343	143,284
Level 2 of fair value hierarchy [member] | Pledged in money market operations | Securities issued or secured by Colombian Government
Disclosure of financial assets [line items]
Financial assets pledged as collateral		137,298
Level 2 of fair value hierarchy [member] | Pledged in money market operations | Securities issued or secured by other Colombian Government entities
Disclosure of financial assets [line items]
Financial assets pledged as collateral		1,006
Level 2 of fair value hierarchy [member] | Pledged in money market operations | Securities issued or secured by other financial entities
Disclosure of financial assets [line items]
Financial assets pledged as collateral	$ 71,343	$ 4,980