Stock Award Plans and Stock-Based Compensation - Additional Information (Detail) (USD $)	12 Months Ended							1 Months Ended		12 Months Ended	1 Months Ended	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2013 Stock Options	Mar. 31, 2013 Restricted Stock and Restricted Stock Units	Mar. 31, 2012 Restricted Stock and Restricted Stock Units	Mar. 31, 2011 Restricted Stock and Restricted Stock Units	Jun. 30, 2011 Performance Based Restricted Stock and Restricted Stock Units	May 31, 2011 Performance Based Restricted Stock and Restricted Stock Units	Mar. 31, 2013 Performance Based Restricted Stock and Restricted Stock Units	May 31, 2012 Performance Based Restricted Stock and Restricted Stock Units Share Based Awards	Mar. 31, 2013 Employee Stock Purchase Plan	Mar. 31, 2012 Employee Stock Purchase Plan	Mar. 31, 2011 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock award plans, outstanding stock options expiration period	10 years
Description of share counts for awards other than 2008 Stock Incentive Plan	Each share of stock issued pursuant to any other type of award counts as 1.58 shares against the maximum number of shares issuable under the Plan for grants made on or after August 11, 2010 (and as 1.5 shares for grants made prior to that date).
Shares available for future issuance under the Plan	2,405,300
Unrecognized stock-based compensation expense				$ 3,600,000	$ 9,300,000					$ 3,900,000
Unrecognized stock-based compensation expense, weighted-average recognition period				2 years 8 months 12 days	1 year 8 months 12 days					1 year 9 months 18 days
Aggregate intrinsic value of options exercised in period	4,600,000	13,400,000	400,000
Proceeds from the exercise of stock options	2,936,000	14,257,000	1,061,000
Fair value of options vested in period	2,600,000	3,800,000	4,500,000
Weighted average grant-date fair value for options granted	$ 9.66	$ 8.35	$ 4.72
Expected dividend yield	0.00%
Weighted average grant-date fair value for restricted stock and restricted stock units granted					$ 21.82	$ 18.13	$ 10.00
Fair value of restricted stock and restricted stock units vested in period					3,000,000	1,500,000	1,000,000
Shares of award granted					400,000			284,000	284,000		195,188
Shares of award granted, performance target met										184,000
Shares of award granted, it is probable that the prescribed performance targets will be met										100,000
Stock-based compensation	$ 9,501,000	$ 7,773,000	$ 5,421,000							$ 3,800,000		$ 198,000	$ 148,000	$ 104,000
ESPP, exercise price as a percentage of its market price	85.00%