Stock Based Compensation and Stock Options - Outstanding Options (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options outstanding, beginning balance	1,102,919	1,135,586	1,115,465	1,163,179
Granted, Number of Options	143,750	155,275	234,250	242,275
Exercised, Number of Options	(4,256)	(44,077)	(95,472)	(139,718)
Cancelled - forfeited, Number of Options	(1,806)
Cancelled - expired, Number of Options	(1,744)
Options outstanding, ending balance	1,238,863	1,230,798	1,238,863	1,230,798
Options vested and expected to vest, Number of Options	1,079,830		1,079,830
Ending exercisable, Number of Options	568,058		568,058
Options outstanding, beginning, Weighted Average Exercise Price	$ 32.17	$ 28.81	$ 29.67	$ 27.65
Granted, Weighted Average Exercise Price per Share	32.10	34.78	36.90	34.44
Exercised, Weighted Average Exercise Price per Share	25.86	23.75	22.05	19.64
Cancelled - forfeited, Weighted Average Exercise Price per Share	40.72
Cancelled - expired, Weighted Average Exercise Price per Share	33.49
Options outstanding, ending, Weighted Average Exercise Price	32.17	$ 29.67	32.17	$ 29.67
Options vested and expected to vest, Weighted Average Exercise Price per Share	31.71		31.71
Ending exercisable, Weighted Average Exercise Price per Share	$ 27.09		$ 27.09
Option outstanding, Weighted Average Remaining Contractual Life (Years)	3 years 2 months 9 days
Options vested and expected to vest, Weighted Average Remaining Contractual Life (Years)	3 years 15 days
Ending exercisable, Weighted Average Remaining Contractual Life (Years)	2 years 3 months 26 days
Option outstanding, Aggregate Intrinsic Value	$ 7,560,784		$ 7,560,784
Options vested and expected to vest, Aggregate Intrinsic Value	7,167,890		7,167,890
Ending exercisable, Aggregate Intrinsic Value	$ 6,078,397		$ 6,078,397