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Movement in Provision for Credit Card and Debit Card Reward Points (Detail) - Debit and Credit Cards Reward Points
₨ in Millions, $ in Millions
 12 Months Ended
Mar. 31, 2020
INR (₨)
Mar. 31, 2020
USD ($)
Mar. 31, 2019
INR (₨)
Valuation and Qualifying Accounts Disclosure [Line Items]      
Opening provision of reward points ₨ 6,030.9 $ 80.0 ₨ 4,711.2
Provision made during the year 5,356.0 71.0 3,747.3
Utilization/write back of provision (3,868.8) (51.3) (2,555.9)
Closing provision of reward points 7,341.5 97.4 6,030.9
Change in Rate of Accrual of Reward Points      
Valuation and Qualifying Accounts Disclosure [Line Items]      
Effect of change in rate of accrual of points/cost of reward (176.6) (2.3) 91.5
Change in Cost of Reward Points      
Valuation and Qualifying Accounts Disclosure [Line Items]      
Effect of change in rate of accrual of points/cost of reward ₨ 0.0 $ 0.0 ₨ 36.8