Consolidated Statements of Operations - USD ($)	12 Months Ended
	Jul. 31, 2018	Jul. 31, 2017		Jul. 31, 2016
Income Statement [Abstract]
Net Sales	$ 570,589,000	$ 550,368,000		$ 411,004,000
Cost of sales	346,648,000	332,183,000		239,767,000
Gross profit	223,941,000	218,185,000		171,237,000
Expenses:
Selling, general and administrative	113,922,000	116,080,000		94,932,000
Research and development	53,869,000	54,260,000		42,190,000
Amortization of intangibles	21,075,000	22,823,000		13,415,000
Settlement of intellectual property litigation	0	(12,020,000)		0
Acquisition plan expenses	0	0		21,276,000
Total operating expenses	188,866,000	181,143,000		171,813,000
Operating income (loss)	35,075,000	37,042,000		(576,000)
Other expenses (income):
Interest expense	10,195,000	11,629,000		7,750,000
Interest (income) and other	254,000	(68,000)		(134,000)
Income (loss) before (benefit from) provision for income taxes	24,626,000	25,481,000		(8,192,000)
(Benefit from) provision for income taxes	(5,143,000)	9,654,000		(454,000)
Net income (loss)	$ 29,769,000	$ 15,827,000		$ (7,738,000)
Net income (loss) per share:
Basic (in dollars per share)	$ 1.25	$ 0.68		$ (0.46)
Diluted (in dollars per share)	$ 1.24	$ 0.67	[1]	$ (0.46)
Weighted average number of common shares outstanding - basic (in shares)	23,825,000	23,433,000		16,972,000
Weighted average number of common and common equivalent shares outstanding - diluted (in shares)	24,040,000	23,489,000		16,972,000
Dividends declared per issued and outstanding common share as of the applicable dividend record date (in dollars per share)	$ 0.4	$ 0.60		$ 1.20

[1] The per share information is computed independently for each quarter and the full year based on the respective weighted average number of common shares outstanding. Therefore, income per share information for the full fiscal year may not equal the total of the quarters within the year.