Financial instruments - Aggregate Notional Principal Amounts of Bank's Outstanding Forward Exchange and Derivative Contracts (Detail) ₨ in Millions, $ in Millions	Mar. 31, 2025 INR (₨)	Mar. 31, 2025 USD ($)	Mar. 31, 2024 INR (₨)
Derivatives, Fair Value [Line Items]
Notional	₨ 24,496,285.6	$ 286,741.0	₨ 21,269,897.6
Gross Assets	179,812.4	2,104.8	109,038.5
Gross Liabilities	143,566.1	1,680.5	109,409.9
Net Fair Value	36,246.3	424.4	(371.4)
Interest rate derivatives
Derivatives, Fair Value [Line Items]
Notional	10,191,133.7	119,292.2	7,834,342.2
Gross Assets	58,654.3		53,970.3
Gross Liabilities	48,979.2		63,112.8
Net Fair Value	9,675.1	113.3	(9,142.5)
Forward rate agreements
Derivatives, Fair Value [Line Items]
Notional	615,831.9	7,208.6	592,414.5
Gross Assets	15,507.0		10,071.3
Gross Liabilities	5,676.8		4,514.9
Net Fair Value	9,830.2	115.1	5,556.4
Currency options
Derivatives, Fair Value [Line Items]
Notional	291,621.4	3,413.6	223,904.8
Gross Assets	1,065.3		588.1
Gross Liabilities	1,332.6		873.2
Net Fair Value	(267.3)	(3.1)	(285.1)
Currency swaps
Derivatives, Fair Value [Line Items]
Notional	462,773.9	5,417.0	493,708.2
Gross Assets	19,180.2		11,754.5
Gross Liabilities	4,360.8		4,440.2
Net Fair Value	14,819.4	173.5	7,314.3
Forward exchange contracts
Derivatives, Fair Value [Line Items]
Notional	12,934,924.7	151,409.6	12,125,527.9
Gross Assets	85,405.6		32,654.3
Gross Liabilities	83,216.7		36,468.8
Net Fair Value	₨ 2,188.9	$ 25.6	₨ (3,814.5)

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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