Expiration Years of Minimum Alternate Tax Credit (Detail) (Minimum Alternate Tax (MAT), USD $) In Millions, unless otherwise specified	Mar. 31, 2013
Tax Credit Carryforward [Line Items]
Minimum Alternate tax credit	$ 17.55
2017-18
Tax Credit Carryforward [Line Items]
Minimum Alternate tax credit	0.24
2018-19
Tax Credit Carryforward [Line Items]
Minimum Alternate tax credit	0.33
2019-20
Tax Credit Carryforward [Line Items]
Minimum Alternate tax credit	4.04
2020-21
Tax Credit Carryforward [Line Items]
Minimum Alternate tax credit	6.04
2021-22
Tax Credit Carryforward [Line Items]
Minimum Alternate tax credit	0.97
2022-23
Tax Credit Carryforward [Line Items]
Minimum Alternate tax credit	$ 5.93