Stock Options and Stock-Based Compensation - Stock Options Outstanding and Exercisable (Detail) - $ / shares	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Outstanding Options	1,143,928	1,115,465	1,163,179	1,115,984
Weighted Average Remaining Contractual Life	3 years 1 month 13 days
Outstanding Options – Weighted Average Exercise Price	$ 32.02	$ 30.36	$ 27.65
Exercisable Options – Number of Exercisable Options	585,424
Exercisable Options – Weighted Average Exercise Price	$ 27.63
Range of Exercise Price, $12.71 to $23.10 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Price, lower limit	12.71
Range of Exercise Price, upper limit	$ 23.10
Number of Outstanding Options	324,027
Weighted Average Remaining Contractual Life	2 years 22 days
Outstanding Options – Weighted Average Exercise Price	$ 20.39
Exercisable Options – Number of Exercisable Options	317,225
Exercisable Options – Weighted Average Exercise Price	$ 20.33
Range of Exercise Price, $23.11 to $34.77 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Price, lower limit	23.11
Range of Exercise Price, upper limit	$ 34.77
Number of Outstanding Options	320,585
Weighted Average Remaining Contractual Life	3 years 8 months 2 days
Outstanding Options – Weighted Average Exercise Price	$ 31.47
Exercisable Options – Number of Exercisable Options	120,078
Exercisable Options – Weighted Average Exercise Price	$ 29.62
Range of Exercise Price, $34.78 to $40.57 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Price, lower limit	34.78
Range of Exercise Price, upper limit	$ 40.57
Number of Outstanding Options	293,728
Weighted Average Remaining Contractual Life	3 years 4 months 20 days
Outstanding Options – Weighted Average Exercise Price	$ 36.64
Exercisable Options – Number of Exercisable Options	75,579
Exercisable Options – Weighted Average Exercise Price	$ 38.39
Range of Exercise Price, $40.58 to $45.73 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Price, lower limit	40.58
Range of Exercise Price, upper limit	$ 45.73
Number of Outstanding Options	205,588
Weighted Average Remaining Contractual Life	3 years 6 months 29 days
Outstanding Options – Weighted Average Exercise Price	$ 44.61
Exercisable Options – Number of Exercisable Options	72,542
Exercisable Options – Weighted Average Exercise Price	$ 45.04