Fair Value Measurement Hierarchy - Summary of Fair Value Hierarchy, Valuation Techniques And Inputs (Detail)	12 Months Ended
Mar. 31, 2025	Mar. 31, 2024
Market value techniques \| Forward foreign currency exchange rates, interest rates to discount future cash flows \| Derivative instruments - hedge instruments \| Financial liabilities designated as a hedge instrument at fair value \| Level 2
Financial liabilities measured at amortised cost
Valuation technique	Market value techniques	Market value techniques
Inputs used	Forward foreign currency exchange rates, interest rates to discount future cash flows	Forward foreign currency exchange rates, interest rates to discount future cash flows
Market value techniques \| Volume Weight Average Price of the Company shares over 30 trading days \| Liability for put options with non-controlling interests \| Financial liabilities at fair value \| Level 2
Financial liabilities measured at amortised cost
Valuation technique	Market value techniques	Market value techniques
Inputs used	Volume Weight Average Price of the Company shares over 30 trading days	Volume Weight Average Price of the Company shares over 30 trading days
Market value techniques \| Market value of warrants \| Derivative instruments - public share warrants \| Financial liabilities at fair value through profit or loss \| Level 1
Financial liabilities measured at amortised cost
Valuation technique	Market value techniques	Market value techniques
Inputs used	Market value of warrants	Market value of warrants
Market value techniques \| Market Value of Investment \| Financial assets measured at fair value through profit or loss \| Investments \| Level 2
Financial assets measured at amortised cost
Valuation technique	Market value techniques	Market value techniques
Inputs used	Market value of investments	Market value of investments
Black Scholes method \| Interest rates to discount future cash flows, share price and public share warrant price \| Derivative instruments - private share warrants \| Financial liabilities at fair value through profit or loss \| Level 2
Financial liabilities measured at amortised cost
Valuation technique	Black Scholes method	Black Scholes method
Inputs used	Interest rates to discount future cash flows, share price and public share warrant price	Interest rates to discount future cash flows, share price and public share warrant price
Derivative instruments - hedge instruments \| Market value techniques \| Forward foreign currency exchange rates, interest rates to discount future cash flows \| Financial assets designated as a hedge instrument at fair value \| Level 2
Financial assets measured at amortised cost
Valuation technique	Market value techniques	Market value techniques
Inputs used	Forward foreign currency exchange rates, interest rates to discount future cash flows	Forward foreign currency exchange rates, interest rates to discount future cash flows

The description of inputs used in the fair value measurement of assets. Inputs are the assumptions that market participants would use when pricing the asset, including assumptions about risk such as the risk inherent in a particular valuation technique used to measure fair value (such as a pricing model) and the risk inherent in the inputs to the valuation technique.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 13
-IssueDate 2024-01-01
-Paragraph 93
-Subparagraph d
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=13&code=ifrs-tx-2024-en-r&anchor=para_93_d&doctype=Standard
-URIDate 2024-03-27

+ Details

Name:	ifrs-full_DescriptionOfInputsUsedInFairValueMeasurementAssets
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The description of inputs used in the fair value measurement of liabilities. Inputs are the assumptions that market participants would use when pricing the liability, including assumptions about risk such as the risk inherent in a particular valuation technique used to measure fair value (such as a pricing model) and the risk inherent in the inputs to the valuation technique.

+ References

+ Details

Name:	ifrs-full_DescriptionOfInputsUsedInFairValueMeasurementLiabilities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The description of the valuation techniques (for example, the market approach, cost approach and income approach) used for the fair value measurement of assets. [Refer: Valuation techniques used in fair value measurement [domain]; Cost approach [member]; Income approach [member]; Market approach [member]]

+ References

+ Details

Name:	ifrs-full_DescriptionOfValuationTechniquesUsedInFairValueMeasurementAssets
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The description of the valuation techniques (for example, the market approach, cost approach and income approach) used for the fair value measurement of liabilities. [Refer: Valuation techniques used in fair value measurement [domain]; Cost approach [member]; Income approach [member]; Market approach [member]]

+ References

+ Details

Name:	ifrs-full_DescriptionOfValuationTechniquesUsedInFairValueMeasurementLiabilities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Financial assets measured at amortised cost.

+ References

No definition available.

+ Details

Name:	rnw_FinancialAssetsMeasuredAtAmortisedCostAbstract
Namespace Prefix:	rnw_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Financial liabilities measured at amortised cost.

+ References

No definition available.

+ Details

Name:	rnw_FinancialLiabilitiesMeasuredAtAmortisedCostAbstract
Namespace Prefix:	rnw_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration