RISK MANAGEMENT - Credit risk model - Impairment losses (Details) - COP ($) $ in Millions	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]
Impairment loss	$ 3,538,900	$ 4,046,323	$ 4,029,479
Loss allowance - costs and expenses of sales goods and services	(56,497)	(71,157)	(51,035)
Financial assets at amortised cost, category [member]
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]
Impairment loss	4,324,724	4,686,752	4,647,047
Financial assets at amortised cost, category [member] \| Loan portfolio [member]
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]
Impairment loss	4,163,320	4,594,708	4,570,560
Financial assets at amortised cost, category [member] \| Commercial lending portfolio [member]
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]
Impairment loss	953,167	690,828	137,906
Financial assets at amortised cost, category [member] \| Interbank and overnight funds [member]
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]
Impairment loss	(647)	773	(1,422)
Financial assets at amortised cost, category [member] \| Loans to consumers [member]
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]
Impairment loss	3,034,991	3,780,124	4,342,925
Financial assets at amortised cost, category [member] \| Mortgages [member]
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]
Impairment loss	175,898	133,885	59,250
Financial assets at amortised cost, category [member] \| Microcredit [member]
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]
Impairment loss	(89)	(10,902)	31,901
Financial assets at amortised cost, category [member] \| Other accounts receivable at amortized cost [member]
Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]
Impairment loss	$ 161,404	$ 92,044	$ 76,487

Disclosure of reconciliation of changes in loss allowance and explanation of changes in gross carrying amount for financial instruments [line items]