Reconciliation of Income Taxes at Indian Statutory Income Tax Rate to Income Tax Expense as Reported (Detail) ₨ in Millions, $ in Millions	12 Months Ended
Mar. 31, 2019 INR (₨)	Mar. 31, 2019 USD ($)	Mar. 31, 2018 INR (₨)	Mar. 31, 2017 INR (₨)
Reconciliation of Estimated Income Taxes to Income Tax Expense as Reported [Line Items]
Income before income tax expense	₨ 339,959.0	$ 4,915.5	₨ 277,106.4	₨ 219,965.5
Statutory income tax rate	34.94%	34.94%	34.61%	34.61%
Expected income tax expense	₨ 118,795.3	$ 1,717.7	₨ 95,901.0	₨ 76,125.7
Adjustments to reconcile expected income tax to actual tax expense
Interest on income tax refund	(343.0)	(5.0)	0.0	0.0
Stock-based compensation	1,867.2	27.0	2,282.3	2,839.0
Income exempt from taxes	(1,422.8)	(20.6)	(524.8)	(997.2)
Effect of change in statutory tax rate	0.0	0.0	(209.2)	0.0
Other, net	496.8	7.2	823.2	1,257.4
Income tax expense	₨ 119,393.5	$ 1,726.3	₨ 98,272.5	₨ 79,224.9

Interest On Income Tax Refund net of tax.

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Reconciliation of Estimated Income Taxes to Income Tax Expense as Reported [Line Items]

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations, attributable to increase (decrease) in the income tax rates.

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The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

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Amount of reported income tax expense (benefit) in excess of (less than) expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operation, attributable to nondeductible expense for award under share-based payment arrangement. Includes, but is not limited to, expense determined to be nondeductible upon grant or after for award under share-based payment arrangement.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to income (loss) exempt from income taxes.

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