Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended				9 Months Ended
	Jan. 31, 2015		Jan. 31, 2014		Jan. 31, 2015		Jan. 31, 2014
Income Statement [Abstract]
Net sales	$ 130,550		$ 145,881		$ 370,865		$ 456,195
Cost of sales	86,726		87,230		243,083		266,834
Gross profit	43,824		58,651		127,782		189,361
Operating expenses:
Research and development	1,901		1,456		4,830		4,119
Selling and marketing	10,088		8,921		26,884		24,150
General and administrative	16,136		17,154		43,765		53,184
Total operating expenses	28,125		27,531		75,479		81,453
Operating income	15,699		31,120		52,303		107,908
Other (expense)/income:
Other (expense)/income, net	16		(6)		(1)		35
Interest income	240		33		284		143
Interest expense	(3,192)		(1,771)		(8,090)		(10,490)
Total other (expense)/income, net	(2,936)		(1,744)		(7,807)		(10,312)
Income from continuing operations before income taxes	12,763		29,376		44,496		97,596
Income tax expense	4,585		9,319		16,611		33,868
Income from continuing operations	8,178		20,057		27,885		63,728
Discontinued operations:
Loss from operations of discontinued security solutions division	(88)		(75)		(245)		(349)
Income tax benefit	(31)		(803)		(85)		(870)
(Loss)/income from discontinued operations	(57)		728		(160)		521
Net income	$ 8,121		$ 20,785		$ 27,725		$ 64,249
Net income per share:
Basic - continuing operations	$ 0.15	[1]	$ 0.36	[1]	$ 0.52	[1]	$ 1.07	[1]
Basic - total	$ 0.15	[1]	$ 0.37	[1]	$ 0.51	[1]	$ 1.07	[1]
Diluted - continuing operations	$ 0.15	[1]	$ 0.35	[1]	$ 0.50	[1]	$ 1.03	[1]
Diluted - total	$ 0.15	[1]	$ 0.36	[1]	$ 0.50	[1]	$ 1.04	[1]
Weighted average number of common shares outstanding:
Basic	53,724		55,583		54,033		59,815
Diluted	54,859		57,024		55,258		62,065

[1] Net income per share may not equal earnings per share from continuing operations plus discontinued operations due to rounding.