Stock Based Compensation and Stock Options - Stock Options Outstanding and Exercisable (Detail) (USD $)	9 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Mar. 31, 2012
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Outstanding Options	1,260,568	1,191,251	1,100,930	1,191,588	1,264,530	1,502,046
Weighted Average Remaining Contractual Life	3 years 7 months 2 days
Outstanding Options - Weighted Average Exercise Price	$ 22.85	$ 20.39	$ 18.65	$ 17.88	$ 17.71	$ 17.10
Exercisable Options - Number of Exercisable Options	467,790
Exercisable Options - Weighted Average Exercise Price	$ 15.71
Range of Exercise Price, $ 7.78 to $ 18.28 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Price, lower limit	$ 7.78
Range of Exercise Price, upper limit	$ 18.28
Number of Outstanding Options	337,181
Weighted Average Remaining Contractual Life	2 years 1 month 21 days
Outstanding Options - Weighted Average Exercise Price	$ 12.72
Exercisable Options - Number of Exercisable Options	318,009
Exercisable Options - Weighted Average Exercise Price	$ 12.65
Range of Exercise Price, $18.29 to $ 23.07 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Price, lower limit	$ 18.29
Range of Exercise Price, upper limit	$ 23.07
Number of Outstanding Options	293,427
Weighted Average Remaining Contractual Life	4 years 2 months 9 days
Outstanding Options - Weighted Average Exercise Price	$ 21.88
Exercisable Options - Number of Exercisable Options	117,256
Exercisable Options - Weighted Average Exercise Price	$ 21.48
Range of Exercise Price, $ 23.08 to $ 24.64 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Price, lower limit	$ 23.08
Range of Exercise Price, upper limit	$ 24.64
Number of Outstanding Options	322,109
Weighted Average Remaining Contractual Life	4 years 1 month 17 days
Outstanding Options - Weighted Average Exercise Price	$ 23.61
Exercisable Options - Number of Exercisable Options	12,792
Exercisable Options - Weighted Average Exercise Price	$ 23.84
Range of Exercise Price, $ 24.65 to $ 40.24 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Price, lower limit	$ 24.65
Range of Exercise Price, upper limit	$ 40.24
Number of Outstanding Options	307,851
Weighted Average Remaining Contractual Life	4 years 22 days
Outstanding Options - Weighted Average Exercise Price	$ 34.08
Exercisable Options - Number of Exercisable Options	19,733
Exercisable Options - Weighted Average Exercise Price	$ 25.41