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, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Effect on basic earnings per share	$ (1.37)	$ (1.16)	$ (2.63)	$ (2.32)
Effect on diluted earnings per share	$ (1.35)	$ (1.15)	$ (2.6)	$ (2.29)
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	$ 1,482,000	$ 1,301,000	$ 2,552,000	$ 2,613,000
Amount of income tax benefit recognized	(273,000)	(254,000)	(528,000)	(544,000)
Amount charged against net income	$ 1,209,000	$ 1,047,000	$ 2,024,000	$ 2,069,000
Effect on basic earnings per share	$ (0.07)	$ (0.06)	$ (0.12)	$ (0.12)
Effect on diluted earnings per share	$ (0.07)	$ (0.06)	$ (0.12)	$ (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	$ 723,000	$ 679,000	$ 1,438,000	$ 1,347,000
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	$ 759,000	$ 622,000	$ 1,114,000	$ 1,266,000