Reconciliation of Net Income (Loss) Amounts and Weighted Average Number of Common and Common Equivalent Shares Used to Determine Basic and Diluted Earnings (Loss) per Common Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Apr. 30, 2014	Jan. 31, 2014	Oct. 31, 2013	Jul. 31, 2013	Apr. 30, 2013	Jan. 31, 2013	Oct. 31, 2012	Jul. 31, 2012	Apr. 30, 2014		Apr. 30, 2013		Apr. 30, 2012
Net income/(loss)
Income from continuing operations	$ 24,899	$ 20,057	$ 17,145	$ 26,526	$ 28,630	$ 17,506	$ 16,401	$ 18,869	$ 88,627		$ 81,406		$ 26,433
Income/(loss) from discontinued operations, net of tax	157	728	(158)	(49)	(3,464)	(2,930)	4,784	(1,083)	678	[1]	(2,693)	[1]	(10,328)	[1]
Net income/(loss)	$ 25,056	$ 20,785	$ 16,987	$ 26,477	$ 25,166	$ 14,576	$ 21,184	$ 17,787	$ 89,305		$ 78,713		$ 16,105
Weighted average shares outstanding - Basic									58,668		65,155		64,788
Dilutive effect of stock option and award plans									1,446		1,487		965
Dilutive effect of conversion of convertible debt													1,524
Diluted shares outstanding									60,114		66,642		67,277
Earnings per share - Basic
Income from continuing operations	$ 0.45	$ 0.36	$ 0.29	$ 0.41	$ 0.45	$ 0.27	$ 0.25	$ 0.29	$ 1.51		$ 1.25		$ 0.41
Income/(loss) from discontinued operations									$ 0.01		$ (0.04)		$ (0.16)
Net income/(loss)	$ 0.45	$ 0.37	$ 0.28	$ 0.41	$ 0.39	$ 0.22	$ 0.32	$ 0.27	$ 1.52		$ 1.21		$ 0.25
Earnings per share - Diluted
Income from continuing operations	$ 0.44	$ 0.35	$ 0.28	$ 0.40	$ 0.44	$ 0.26	$ 0.24	$ 0.28	$ 1.47	[2]	$ 1.22	[2]	$ 0.40	[2]
Income/(loss) from discontinued operations									$ 0.01	[2]	$ (0.04)	[2]	$ (0.15)	[2]
Net income/(loss)	$ 0.44	$ 0.36	$ 0.28	$ 0.40	$ 0.38	$ 0.22	$ 0.31	$ 0.27	$ 1.49	[2]	$ 1.18	[2]	$ 0.25	[2]

[1] The loss before income taxes for fiscal 2014 related primarily to legal fees associated with retained liabilities. The favorable income tax benefit in fiscal 2014 was a result of the reversal of an uncertain tax position whose statute of limitations had expired. Included in the results of operations for fiscal 2013 and 2012 are $1.2 million and $5.5 million, respectively, of non-cash charges related to the loss on sale from the divestiture of our discontinued security solutions division.

[2] Included in the calculation for diluted earnings per common share for the year ended April 30, 2012 is $499,000 of diluted earnings related to the effect of conversion of convertible debt.