Stock-Based Compensation and Stock Options - Stock Options (Detail) - $ / shares	3 Months Ended		9 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options outstanding, beginning balance, Shares	1,068,503	1,102,919	1,143,928	1,115,465
Options granted, Shares	154,500	143,750	305,550	234,250
Options exercised, Shares	(51,712)	(4,256)	(263,544)	(95,472)
Options cancelled/forfeited, Shares	(1,420)	(3,550)	(16,063)	(15,380)
Options outstanding, ending balance, Shares	1,169,871	1,238,863	1,169,871	1,238,863
Options outstanding, beginning balance, Weighted Average Exercise Price	$ 35.28	$ 32.17	$ 32.02	$ 29.67
Options granted, Weighted Average Exercise Price	57.75	32.10	52.49	36.90
Options exercised, Weighted Average Exercise Price	31.15	25.86	26.96	22.05
Options cancelled/forfeited, Weighted Average Exercise Price	47.11	37.17	40.90	36.55
Options outstanding, ending balance, Weighted Average Exercise Price	$ 38.41	$ 32.17	$ 38.41	$ 32.17