Segment Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2020	Apr. 30, 2019	Jul. 31, 2019
Segment Reporting Information [Line Items]
Net sales	$ 135,121,000	$ 170,448,000	$ 467,042,000	$ 495,425,000
Operating income (loss)	(3,136,000)	11,296,000	12,358,000	31,002,000
Net income (loss)	(3,989,000)	7,612,000	5,894,000	18,906,000
Provision for (benefit from) income taxes	(759,000)	1,547,000	1,503,000	1,791,000
Interest (income) and other expense	108,000	(22,000)	37,000	(7,000)
Write-off of deferred financing costs	0	0	0	3,217,000
Interest expense	1,504,000	2,159,000	4,924,000	7,095,000
Amortization of stock-based compensation	981,000	1,119,000	3,098,000	3,356,000
Amortization of intangibles	5,517,000	4,536,000	15,952,000	13,113,000
Depreciation	2,650,000	2,918,000	8,022,000	8,618,000
Estimated contract settlement costs	476,000	2,465,000	444,000	6,351,000
Settlement of intellectual property litigation	0	0	0	(3,204,000)
Acquisition plan expenses	5,983,000	1,704,000	14,397,000	4,612,000
Facility exit costs				1,373,000
Adjusted EBITDA	12,471,000	24,038,000	54,271,000	65,221,000
Purchases of property, plant and equipment	1,912,000	2,207,000	4,420,000	6,388,000
Long-lived assets acquired in connection with the acquisitions	8,425,000	60,451,000	40,669,000	60,451,000
Total assets	951,732,000	903,487,000	951,732,000	903,487,000	$ 887,711,000
Unallocated
Segment Reporting Information [Line Items]
Net sales	0	0	0	0
Operating income (loss)	(11,371,000)	(6,883,000)	(30,423,000)	(17,420,000)
Net income (loss)	(11,704,000)	(10,547,000)	(36,501,000)	(29,382,000)
Provision for (benefit from) income taxes	(1,175,000)	1,537,000	1,186,000	1,726,000
Interest (income) and other expense	19,000	(10,000)	1,000	(6,000)
Write-off of deferred financing costs				3,217,000
Interest expense	1,489,000	2,137,000	4,891,000	7,025,000
Amortization of stock-based compensation		1,119,000	3,098,000	3,356,000
Amortization of intangibles	0	0	0	0
Depreciation	210,000	177,000	578,000	607,000
Estimated contract settlement costs	0	0	0	0
Settlement of intellectual property litigation				(3,204,000)
Acquisition plan expenses	5,282,000	1,704,000	13,696,000	4,612,000
Facility exit costs				0
Adjusted EBITDA	(4,898,000)	(3,883,000)	(13,051,000)	(12,049,000)
Purchases of property, plant and equipment	118,000	181,000	286,000	438,000
Long-lived assets acquired in connection with the acquisitions	0	0	0	0
Total assets	52,538,000	37,546,000	52,538,000	37,546,000
Commercial Solutions Segment
Segment Reporting Information [Line Items]
Net sales	78,311,000	89,600,000	268,747,000	254,308,000
Commercial Solutions Segment | Operating Segments
Segment Reporting Information [Line Items]
Net sales	78,311,000	89,600,000	268,747,000	254,308,000
Operating income (loss)	4,041,000	8,126,000	26,501,000	23,942,000
Net income (loss)	3,462,000	8,086,000	26,031,000	23,783,000
Provision for (benefit from) income taxes	481,000	10,000	382,000	65,000
Interest (income) and other expense	89,000	9,000	62,000	32,000
Write-off of deferred financing costs				0
Interest expense	9,000	21,000	26,000	62,000
Amortization of stock-based compensation	0	0	0	0
Amortization of intangibles	4,313,000	3,692,000	13,037,000	10,581,000
Depreciation	1,993,000	2,374,000	6,372,000	6,898,000
Estimated contract settlement costs	476,000	2,465,000	444,000	6,351,000
Settlement of intellectual property litigation				0
Acquisition plan expenses	701,000	0	701,000	0
Facility exit costs				0
Adjusted EBITDA	11,524,000	16,657,000	47,055,000	47,772,000
Purchases of property, plant and equipment	1,263,000	1,730,000	3,178,000	4,593,000
Long-lived assets acquired in connection with the acquisitions	4,023,000	60,451,000	6,060,000	60,451,000
Total assets	663,455,000	665,499,000	663,455,000	665,499,000
Commercial Solutions Segment | Intersegment Eliminations
Segment Reporting Information [Line Items]
Net sales	3,115,000	1,413,000	6,876,000	14,515,000
Government Solutions Segment
Segment Reporting Information [Line Items]
Net sales	56,810,000	80,848,000	198,295,000	241,117,000
Government Solutions Segment | Operating Segments
Segment Reporting Information [Line Items]
Net sales	56,810,000	80,848,000	198,295,000	241,117,000
Operating income (loss)	4,194,000	10,053,000	16,280,000	24,480,000
Net income (loss)	4,253,000	10,073,000	16,364,000	24,505,000
Provision for (benefit from) income taxes	(65,000)	0	(65,000)	0
Interest (income) and other expense	0	(21,000)	(26,000)	(33,000)
Write-off of deferred financing costs				0
Interest expense	6,000	1,000	7,000	8,000
Amortization of stock-based compensation	0	0	0	0
Amortization of intangibles	1,204,000	844,000	2,915,000	2,532,000
Depreciation	447,000	367,000	1,072,000	1,113,000
Estimated contract settlement costs	0	0	0	0
Settlement of intellectual property litigation				0
Acquisition plan expenses	0	0	0	0
Facility exit costs				1,373,000
Adjusted EBITDA	5,845,000	11,264,000	20,267,000	29,498,000
Purchases of property, plant and equipment	531,000	296,000	956,000	1,357,000
Long-lived assets acquired in connection with the acquisitions	4,402,000	0	34,609,000	0
Total assets	$ 235,739,000	$ 200,442,000	$ 235,739,000	$ 200,442,000