INVESTMENT SECURITIES - Investments in debt securities at fair value through OCI (Details) - COP ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
INVESTMENT SECURITIES
Redemptions or sales	$ 232,738	$ 43,574
ECL allowance	53,511	31,809
Total reclassified to profit or loss	$ 286,249	$ 75,383

Amount of expected credit loss allowance reclassified from other comprehensive income before tax to profit or loss.

No definition available.

Name:	aval_ExpectedCreditLossAllowancesReclassifiedFromOCIBeforeTaxToProfitOrLoss
Namespace Prefix:	aval_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration