Stock-Based Compensation and Stock Options - Stock Options (Detail) - $ / shares	3 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options outstanding, beginning balance, Shares	1,064,439	1,143,928
Options granted, Shares	56,800	77,400
Options exercised, Shares	(54,238)	(65,921)
Options cancelled/forfeited, Shares	(3,747)	(3,685)
Options outstanding, ending balance, Shares	1,063,254	1,151,722
Options outstanding, beginning balance, Weighted Average Exercise Price	$ 39.45	$ 32.02
Options granted, Weighted Average Exercise Price	49.40	45.93
Options exercised, Weighted Average Exercise Price	30.84	26.67
Options cancelled/forfeited, Weighted Average Exercise Price	39.76	39.99
Options outstanding, ending balance, Weighted Average Exercise Price	$ 40.43	$ 33.24