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Risk management - Risk principles and culture (Details) | 12 Months Ended
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Dec. 31, 2025 linesOfDefense
Risk Management [Abstract] |
Risk management and control model, number of lines of defense | 3

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- References No definition available. + Details
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- Definition The number of lines of defense which form the base of the risk management and control model. + References No definition available. + Details
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Namespace Prefix: | san_
Data Type: | xbrli:integerItemType
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Period Type: | duration