Income Taxes - Additional Information (Detail) ₨ in Millions, $ in Millions	Mar. 31, 2015 INR (₨)	Mar. 31, 2015 USD ($)	Mar. 31, 2014 INR (₨)	Mar. 31, 2014 USD ($)	Mar. 31, 2013 INR (₨)
Income Taxes [Line Items]
Total unrecognized tax benefit	₨ 648.3	$ 10.4	₨ 648.3	$ 10.4	₨ 648.3
The total unrecognized tax benefits, if recognized, that would reduce the tax provisions and thereby affect the effective tax rate	₨ 648.3

Amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 15A

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6907707&loc=SL6600010-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Unrecognized Tax Benefit

-URI http://asc.fasb.org/extlink&oid=6527854

Name:	us-gaap_UnrecognizedTaxBenefits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant