Stock Options and Stock-Based Compensation - Stock Options (Detail) - $ / shares	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding, beginning balance	1,115,465	1,163,179	1,115,984
Options granted, Shares	267,950	276,275	241,625
Options exercised, Shares	(115,592)	(200,753)	(111,758)
Options cancelled/forfeited, Shares	(123,895)	(123,236)	(82,672)
Options outstanding, ending balance	1,143,928	1,115,465	1,163,179
Options granted, weighted average exercise price	$ 37.13	$ 35.51	$ 37.64
Options exercised, weighted average exercise price	22.74	19.75	17.27
Options cancelled/forfeited, weighted average exercise price	36.90	33.44	32.31
Weighted average exercise price per share	$ 32.02	$ 30.36	$ 27.65
Options available for future grants	505,493	650,345	800,342
Exercisable options	585,424	529,691	559,168
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Price range of outstanding options	$ 12.71	$ 9.05	$ 7.78
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Price range of outstanding options	$ 45.73	$ 45.55	$ 45.55