Summary of Significant Accounting and Reporting Policies (Disaggregation of Revenue) (Details) - USD ($)	3 Months Ended												12 Months Ended
	Jul. 31, 2021	Apr. 30, 2021	Jan. 31, 2021	Oct. 31, 2020	Jul. 31, 2020	Apr. 30, 2020	Jan. 31, 2020	Oct. 31, 2019	Jul. 31, 2019	Apr. 30, 2019	Jan. 31, 2019	Oct. 31, 2018	Jul. 31, 2021	Jul. 31, 2020	Jul. 31, 2019
Disaggregation of Revenue [Line Items]
Net sales	$ 145,809,000	$ 139,376,000	$ 161,292,000	$ 135,218,000	$ 149,673,000	$ 135,121,000	$ 161,654,000	$ 170,267,000	$ 176,372,000	$ 170,448,000	$ 164,133,000	$ 160,844,000	$ 581,695,000	$ 616,715,000	$ 671,797,000
Point in time
Disaggregation of Revenue [Line Items]
Net sales													236,394,000	278,966,000	353,157,000
Over time
Disaggregation of Revenue [Line Items]
Net sales													345,301,000	337,749,000	318,640,000
Firm fixed-price
Disaggregation of Revenue [Line Items]
Net sales													498,888,000	528,092,000	582,250,000
Cost reimbursable
Disaggregation of Revenue [Line Items]
Net sales													82,807,000	88,623,000	89,547,000
U.S. government
Disaggregation of Revenue [Line Items]
Net sales													201,081,000	223,363,000	269,242,000
Domestic
Disaggregation of Revenue [Line Items]
Net sales													241,671,000	248,245,000	231,948,000
Total United States
Disaggregation of Revenue [Line Items]
Net sales													442,752,000	471,608,000	501,190,000
International
Disaggregation of Revenue [Line Items]
Net sales													138,943,000	145,107,000	170,607,000
Commercial Solutions
Disaggregation of Revenue [Line Items]
Net sales													360,146,000	353,730,000	357,293,000
Commercial Solutions | Point in time
Disaggregation of Revenue [Line Items]
Net sales													141,707,000	142,448,000	177,090,000
Commercial Solutions | Over time
Disaggregation of Revenue [Line Items]
Net sales													218,439,000	211,282,000	180,203,000
Commercial Solutions | Firm fixed-price
Disaggregation of Revenue [Line Items]
Net sales													357,521,000	349,855,000	350,850,000
Commercial Solutions | Cost reimbursable
Disaggregation of Revenue [Line Items]
Net sales													2,625,000	3,875,000	6,443,000
Commercial Solutions | U.S. government
Disaggregation of Revenue [Line Items]
Net sales													52,976,000	52,327,000	68,534,000
Commercial Solutions | Domestic
Disaggregation of Revenue [Line Items]
Net sales													210,493,000	208,284,000	192,516,000
Commercial Solutions | Total United States
Disaggregation of Revenue [Line Items]
Net sales													263,469,000	260,611,000	261,050,000
Commercial Solutions | International
Disaggregation of Revenue [Line Items]
Net sales													96,677,000	93,119,000	96,243,000
Government Solutions
Disaggregation of Revenue [Line Items]
Net sales													221,549,000	262,985,000	314,504,000
Government Solutions | Point in time
Disaggregation of Revenue [Line Items]
Net sales													94,687,000	136,518,000	176,067,000
Government Solutions | Over time
Disaggregation of Revenue [Line Items]
Net sales													126,862,000	126,467,000	138,437,000
Government Solutions | Firm fixed-price
Disaggregation of Revenue [Line Items]
Net sales													141,367,000	178,237,000	231,400,000
Government Solutions | Cost reimbursable
Disaggregation of Revenue [Line Items]
Net sales													80,182,000	84,748,000	83,104,000
Government Solutions | U.S. government
Disaggregation of Revenue [Line Items]
Net sales													148,105,000	171,036,000	200,708,000
Government Solutions | Domestic
Disaggregation of Revenue [Line Items]
Net sales													31,178,000	39,961,000	39,432,000
Government Solutions | Total United States
Disaggregation of Revenue [Line Items]
Net sales													179,283,000	210,997,000	240,140,000
Government Solutions | International
Disaggregation of Revenue [Line Items]
Net sales													$ 42,266,000	$ 51,988,000	$ 74,364,000