Stock Option Plans - Stock Options Outstanding (Detail) (USD $)	12 Months Ended
	Mar. 31, 2014
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Stock Options Outstanding, shares	913,825
Options Outstanding, Weighted-Average Remaining Contractual Life	4 years 7 months 6 days
Options Exercisable, shares	674,565
$4.93—$6.62
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	$ 4.93
Exercise Price Range, Upper Range Limit	$ 6.62
Stock Options Outstanding, shares	376,963
Options Outstanding, Weighted-Average Remaining Contractual Life	1 year 9 months 18 days
Options Exercisable, shares	376,963
$7.30—$8.88
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	$ 7.30
Exercise Price Range, Upper Range Limit	$ 8.88
Stock Options Outstanding, shares	192,809
Options Outstanding, Weighted-Average Remaining Contractual Life	3 years 6 months
Options Exercisable, shares	192,809
$16.94—$19.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	$ 16.94
Exercise Price Range, Upper Range Limit	$ 19.00
Stock Options Outstanding, shares	244,406
Options Outstanding, Weighted-Average Remaining Contractual Life	7 years 9 months 18 days
Options Exercisable, shares	96,793
$30.01—$35.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	$ 30.01
Exercise Price Range, Upper Range Limit	$ 35.00
Stock Options Outstanding, shares	40,000
Options Outstanding, Weighted-Average Remaining Contractual Life	8 years 9 months 18 days
Options Exercisable, shares	8,000
$35.01—$40.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	$ 35.01
Exercise Price Range, Upper Range Limit	$ 40.00
Stock Options Outstanding, shares	22,867
Options Outstanding, Weighted-Average Remaining Contractual Life	9 years 1 month 6 days
Options Exercisable, shares	0
$40.01—$45.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	$ 40.01
Exercise Price Range, Upper Range Limit	$ 45.00
Stock Options Outstanding, shares	36,780
Options Outstanding, Weighted-Average Remaining Contractual Life	9 years 3 months 18 days
Options Exercisable, shares	0