Weighted Average Assumptions Used to Calculate Fair Value of Options Granted (Detail)	12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Risk-free interest rate	1.60%	0.94%	0.78%
Expected option life (years)	4 years 2 months 9 days	4 years 3 months	4 years 3 months 22 days
Expected volatility	49.30%	51.70%	56.20%