Segment Information (Details) - USD ($)	3 Months Ended			6 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Oct. 31, 2018	Jan. 31, 2020	Jan. 31, 2019	Jul. 31, 2019
Segment Reporting Information [Line Items]
Net sales	$ 161,654,000	$ 164,133,000		$ 331,921,000	$ 324,977,000
Operating income (loss)	6,234,000	12,413,000		15,494,000	19,706,000
Net income (loss)	3,495,000	7,826,000		9,883,000	11,294,000
Provision for (benefit from) income taxes	1,117,000	2,371,000		2,262,000	244,000
Interest (income) and other expense	6,000	(51,000)		(71,000)	15,000
Write-off of deferred financing costs	0	0	$ 3,217,000	0	3,217,000
Interest expense	1,616,000	2,267,000		3,420,000	4,936,000
Amortization of stock-based compensation	1,238,000	1,191,000	$ 1,191,000	2,117,000	2,237,000
Amortization of intangibles	5,229,000	4,288,000		10,435,000	8,577,000
Depreciation	2,721,000	2,849,000		5,372,000	5,700,000
Estimated contract settlement costs	(262,000)	3,886,000		(32,000)	3,886,000
Facility exit costs					1,373,000
Adjusted EBITDA	21,185,000	23,201,000		41,800,000	41,183,000
Purchases of property, plant and equipment	1,258,000	2,536,000		2,508,000	4,181,000
Long-lived assets acquired in connection with the acquisition of CGC	31,131,000			31,131,000
Total assets	949,942,000	843,327,000		949,942,000	843,327,000	$ 887,711,000
Acquisition plan expenses	6,025,000	1,778,000		8,414,000	2,908,000
Settlement of intellectual property litigation	0	(3,204,000)		0	(3,204,000)
Unallocated
Segment Reporting Information [Line Items]
Net sales	0	0		0	0
Operating income (loss)	(11,388,000)	(4,128,000)		(19,052,000)	(10,537,000)
Net income (loss)	(14,223,000)	(8,721,000)		(24,797,000)	(18,835,000)
Provision for (benefit from) income taxes	1,229,000	2,328,000		2,361,000	189,000
Interest (income) and other expense	(1,000)	22,000		(18,000)	4,000
Write-off of deferred financing costs					3,217,000
Interest expense	1,607,000	2,243,000		3,402,000	4,888,000
Amortization of stock-based compensation		1,191,000		2,117,000	2,237,000
Amortization of intangibles	0	0		0	0
Depreciation	226,000	186,000		368,000	430,000
Estimated contract settlement costs	0	0		0	0
Facility exit costs					0
Adjusted EBITDA	(3,899,000)	(4,177,000)		(8,153,000)	(8,166,000)
Purchases of property, plant and equipment	142,000	133,000		168,000	257,000
Long-lived assets acquired in connection with the acquisition of CGC	0			0
Total assets	44,385,000	38,215,000		44,385,000	38,215,000
Acquisition plan expenses	6,025,000	1,778,000		8,414,000	2,908,000
Settlement of intellectual property litigation		(3,204,000)			(3,204,000)
Commercial Solutions Segment
Segment Reporting Information [Line Items]
Net sales	96,122,000	86,735,000		190,436,000	164,708,000
Commercial Solutions Segment | Operating Segments
Segment Reporting Information [Line Items]
Net sales	96,122,000	86,735,000		190,436,000	164,708,000
Operating income (loss)	12,619,000	8,758,000		22,460,000	15,816,000
Net income (loss)	12,702,000	8,725,000		22,569,000	15,697,000
Provision for (benefit from) income taxes	(112,000)	43,000		(99,000)	55,000
Interest (income) and other expense	20,000	(29,000)		(27,000)	23,000
Write-off of deferred financing costs					0
Interest expense	9,000	19,000		17,000	41,000
Amortization of stock-based compensation	0	0		0	0
Amortization of intangibles	4,362,000	3,444,000		8,724,000	6,889,000
Depreciation	2,183,000	2,296,000		4,379,000	4,524,000
Estimated contract settlement costs	(262,000)	3,886,000		(32,000)	3,886,000
Facility exit costs					0
Adjusted EBITDA	18,902,000	18,384,000		35,531,000	31,115,000
Purchases of property, plant and equipment	915,000	1,971,000		1,915,000	2,863,000
Long-lived assets acquired in connection with the acquisition of CGC	0			0
Total assets	672,336,000	594,992,000		672,336,000	594,992,000
Acquisition plan expenses	0	0		0	0
Settlement of intellectual property litigation		0			0
Commercial Solutions Segment | Intersegment Eliminations
Segment Reporting Information [Line Items]
Net sales	1,862,000	4,562,000		3,761,000	13,102,000
Government Solutions Segment
Segment Reporting Information [Line Items]
Net sales	65,532,000	77,398,000		141,485,000	160,269,000
Government Solutions Segment | Operating Segments
Segment Reporting Information [Line Items]
Net sales	65,532,000	77,398,000		141,485,000	160,269,000
Operating income (loss)	5,003,000	7,783,000		12,086,000	14,427,000
Net income (loss)	5,016,000	7,822,000		12,111,000	14,432,000
Provision for (benefit from) income taxes	0	0		0	0
Interest (income) and other expense	(13,000)	(44,000)		(26,000)	(12,000)
Write-off of deferred financing costs					0
Interest expense	0	5,000		1,000	7,000
Amortization of stock-based compensation	0	0		0	0
Amortization of intangibles	867,000	844,000		1,711,000	1,688,000
Depreciation	312,000	367,000		625,000	746,000
Estimated contract settlement costs	0	0		0	0
Facility exit costs					1,373,000
Adjusted EBITDA	6,182,000	8,994,000		14,422,000	18,234,000
Purchases of property, plant and equipment	201,000	432,000		425,000	1,061,000
Long-lived assets acquired in connection with the acquisition of CGC	31,131,000			31,131,000
Total assets	233,221,000	210,120,000		233,221,000	210,120,000
Acquisition plan expenses	$ 0	0		$ 0	0
Settlement of intellectual property litigation		$ 0			$ 0