Earnings Per Equity Share - Summary of Diluted Earnings Per Share (Detail) ₨ / shares in Units, $ / shares in Units, ₨ in Millions, $ in Millions	12 Months Ended
Mar. 31, 2018 INR (₨) ₨ / shares shares	Mar. 31, 2018 USD ($) $ / shares shares	Mar. 31, 2017 INR (₨) ₨ / shares shares	Mar. 31, 2016 INR (₨) ₨ / shares shares
Earnings per share [abstract]
Profit attributable to equity holders of the Company	₨ 80,081	$ 1,230	₨ 84,895	₨ 89,075
Weighted average number of equity shares outstanding	4,750,043,400	4,750,043,400	4,857,081,010	4,913,118,800
Effect of dilutive equivalent share options	8,318,575	8,318,575	14,266,128	10,261,016
Weighted average number of equity shares for diluted earnings per share	4,758,361,975	4,758,361,975	4,871,347,138	4,923,379,816
Diluted earnings per share \| (per share)	₨ 16.83	$ 0.26	₨ 17.43	₨ 18.09

The weighted average number of ordinary shares outstanding plus the weighted average number of ordinary shares that would be issued on the conversion of all the dilutive potential ordinary shares into ordinary shares. [Refer: Ordinary shares [member]; Weighted average [member]]

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The amount of profit (loss) attributable to ordinary equity holders of the parent entity (the numerator), divided by the weighted average number of ordinary shares outstanding during the period (the denominator), both adjusted for the effects of all dilutive potential ordinary shares. [Refer: Ordinary shares [member]; Weighted average [member]]

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The number of dilutive potential ordinary shares that relate to the assumed exercise of the entity's share options.

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The profit (loss) attributable to owners of the parent. [Refer: Profit (loss)]

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The number of ordinary shares outstanding at the beginning of the period, adjusted by the number of ordinary shares bought back or issued during the period multiplied by a time-weighting factor.

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