Stock Based Compensation and Stock Options - Stock Compensation Expense for Time Based Options and Performance Based Options (Detail) (USD $)	3 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total cost of stock-based compensation included in income before income tax provision	$ 207,000	$ 82,000
Effect on diluted net income per share	$ 0.39	$ 0.40
Time Based Options [Member] | Performance Based Options [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total cost of stock-based compensation included in income before income tax provision	717,000	405,000
Amount of income tax benefit recognized	(276,000)	(157,000)
Amount charged against net income	441,000	248,000
Effect on diluted net income per share	$ (0.02)	$ (0.01)
Time Based Options [Member] | Performance Based Options [Member] | Cost of revenue [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total cost of stock-based compensation included in income before income tax provision	239,000	136,000
Time Based Options [Member] | Performance Based Options [Member] | General and administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total cost of stock-based compensation included in income before income tax provision	$ 478,000	$ 269,000