Consolidated Statements of Operations - USD ($)	12 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2017
Income Statement [Abstract]
Net sales	$ 671,797,000	$ 570,589,000	$ 550,368,000
Cost of sales	424,357,000	346,648,000	332,183,000
Gross profit	247,440,000	223,941,000	218,185,000
Expenses:
Selling, general and administrative	128,639,000	113,922,000	116,080,000
Research and development	56,407,000	53,869,000	54,260,000
Amortization of intangibles	18,320,000	21,075,000	22,823,000
Settlement of intellectual property litigation	(3,204,000)	0	(12,020,000)
Acquisition plan expenses	5,871,000	0	0
Total operating expenses	206,033,000	188,866,000	181,143,000
Operating income	41,407,000	35,075,000	37,042,000
Other expenses (income):
Interest expense	9,245,000	10,195,000	11,629,000
Write-off of deferred financing costs	3,217,000	0	0
Interest (income) and other	35,000	254,000	(68,000)
Income before provision for (benefit from) income taxes	28,910,000	24,626,000	25,481,000
Provision for (benefit from) income taxes	3,869,000	(5,143,000)	9,654,000
Net income	$ 25,041,000	$ 29,769,000	$ 15,827,000
Net income per share:
Basic (in dollars per share)	$ 1.04	$ 1.25	$ 0.68
Diluted (in dollars per share)	$ 1.03	$ 1.24	$ 0.67
Weighted average number of common shares outstanding - basic (in shares)	24,124,000	23,825,000	23,433,000
Weighted average number of common and common equivalent shares outstanding - diluted (in shares)	24,302,000	24,040,000	23,489,000