Credit substitutes - Impaired Credit Substitutes (Detail) - Debt securities, other than asset and mortgage-backed securities ₨ in Millions, $ in Millions	12 Months Ended
Mar. 31, 2025 INR (₨)	Mar. 31, 2025 USD ($)	Mar. 31, 2024 INR (₨)	Mar. 31, 2025 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Average non-performing credit substitutes	₨ 0	$ 0	₨ 0
Interest income recognized on non-performing credit substitutes	0	$ 0	0
Credit Substitutes
Schedule of Available-for-sale Securities [Line Items]
Gross non-performing credit substitutes	0		0	$ 0
Credit Substitutes by Industry
Schedule of Available-for-sale Securities [Line Items]
Gross non-performing credit substitutes	₨ 0		₨ 0	$ 0

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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+ Details