Provisions - Summary of Reconciliation of Changes In Provision for Decommissioning Costs (Detail) ₨ in Millions, $ in Millions	12 Months Ended
Mar. 31, 2026 INR (₨)	Mar. 31, 2026 USD ($)	Mar. 31, 2025 INR (₨)	Mar. 31, 2024 INR (₨)
Provision for Warranty [Member]
Disclosure of other provisions [line items]
Beginning balance	₨ 42
Arised during the year	223		₨ 42
Ending balance	265	$ 3	42
Provision for decommissioning, restoration and rehabilitation costs [member]
Disclosure of other provisions [line items]
Beginning balance	9,484		10,508	₨ 16,859
Arised during the year	1,103		804	2,429
Disposal of subsidiaries	(85)		(61)	(149)
Unwinding of discount on provisions	695		773	977
Adjustment during the year	(893)		(2,540)	(9,608)
Ending balance	₨ 10,304	$ 110	₨ 9,484	₨ 10,508

The amount of additional other provisions made. [Refer: Other provisions]

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The decrease in other provisions resulting from the loss of control of a subsidiary. [Refer: Other provisions]

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The increase (decrease) in other provisions resulting from a change in discount rate. [Refer: Other provisions]

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The increase (decrease) in other provisions resulting from transfers and changes that the entity does not separately disclose in the same statement or note. [Refer: Other provisions]

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The amount of provisions other than provisions for employee benefits. [Refer: Provisions]

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