Stock-Based Compensation and Stock Options - Stock Compensation Expense for Time Based Options and Performance Based Options (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Effect on basic earnings per share	$ 0.84	$ 0.90	$ 1.80	$ 1.84
Effect on diluted earnings per share	$ 0.83	$ 0.88	$ 1.77	$ 1.81
Time Based Options and Performance Based Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total cost of stock-based compensation included in income before income tax provision	$ 950,000	$ 1,355,000	$ 2,329,000	$ 2,701,000
Amount of income tax benefit recognized	(199,000)	(266,000)	(492,000)	(510,000)
Amount charged against net income	$ 751,000	$ 1,089,000	$ 1,837,000	$ 2,191,000
Effect on basic earnings per share	$ (0.04)	$ (0.06)	$ (0.11)	$ (0.12)
Effect on diluted earnings per share	$ (0.04)	$ (0.06)	$ (0.10)	$ (0.12)
Time Based Options and Performance Based Options [Member] | Cost of Revenues [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total cost of stock-based compensation included in income before income tax provision	$ 628,000	$ 528,000	$ 1,208,000	$ 1,052,000
Time Based Options and Performance Based Options [Member] | General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total cost of stock-based compensation included in income before income tax provision	$ 322,000	$ 827,000	$ 1,121,000	$ 1,649,000