Summary of Significant Accounting and Reporting Policies (Disaggregation of Revenue) (Details) - USD ($)	3 Months Ended												12 Months Ended
	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, 2018	Apr. 30, 2018	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2018
Disaggregation of Revenue [Line Items]
Net sales	$ 149,673,000	$ 135,121,000	$ 161,654,000	$ 170,267,000	$ 176,372,000	$ 170,448,000	$ 164,133,000	$ 160,844,000	$ 167,435,000	$ 147,854,000	$ 133,731,000	$ 121,569,000	$ 616,715,000	$ 671,797,000	$ 570,589,000
Point in time
Disaggregation of Revenue [Line Items]
Net sales													278,966,000	353,157,000
Over time
Disaggregation of Revenue [Line Items]
Net sales													337,749,000	318,640,000
Firm fixed-price
Disaggregation of Revenue [Line Items]
Net sales													528,092,000	582,250,000
Cost reimbursable
Disaggregation of Revenue [Line Items]
Net sales													88,623,000	89,547,000
U.S. government
Disaggregation of Revenue [Line Items]
Net sales													223,363,000	269,242,000
Domestic
Disaggregation of Revenue [Line Items]
Net sales													248,245,000	231,948,000
Total United States
Disaggregation of Revenue [Line Items]
Net sales													471,608,000	501,190,000
International
Disaggregation of Revenue [Line Items]
Net sales													145,107,000	170,607,000
Commercial Solutions
Disaggregation of Revenue [Line Items]
Net sales													353,730,000	357,293,000
Commercial Solutions | Point in time
Disaggregation of Revenue [Line Items]
Net sales													142,448,000	177,090,000
Commercial Solutions | Over time
Disaggregation of Revenue [Line Items]
Net sales													211,282,000	180,203,000
Commercial Solutions | Firm fixed-price
Disaggregation of Revenue [Line Items]
Net sales													349,855,000	350,850,000
Commercial Solutions | Cost reimbursable
Disaggregation of Revenue [Line Items]
Net sales													3,875,000	6,443,000
Commercial Solutions | U.S. government
Disaggregation of Revenue [Line Items]
Net sales													52,327,000	68,534,000
Commercial Solutions | Domestic
Disaggregation of Revenue [Line Items]
Net sales													208,284,000	192,516,000
Commercial Solutions | Total United States
Disaggregation of Revenue [Line Items]
Net sales													260,611,000	261,050,000
Commercial Solutions | International
Disaggregation of Revenue [Line Items]
Net sales													93,119,000	96,243,000
Government Solutions
Disaggregation of Revenue [Line Items]
Net sales													262,985,000	314,504,000
Government Solutions | Point in time
Disaggregation of Revenue [Line Items]
Net sales													136,518,000	176,067,000
Government Solutions | Over time
Disaggregation of Revenue [Line Items]
Net sales													126,467,000	138,437,000
Government Solutions | Firm fixed-price
Disaggregation of Revenue [Line Items]
Net sales													178,237,000	231,400,000
Government Solutions | Cost reimbursable
Disaggregation of Revenue [Line Items]
Net sales													84,748,000	83,104,000
Government Solutions | U.S. government
Disaggregation of Revenue [Line Items]
Net sales													171,036,000	200,708,000
Government Solutions | Domestic
Disaggregation of Revenue [Line Items]
Net sales													39,961,000	39,432,000
Government Solutions | Total United States
Disaggregation of Revenue [Line Items]
Net sales													210,997,000	240,140,000
Government Solutions | International
Disaggregation of Revenue [Line Items]
Net sales													$ 51,988,000	$ 74,364,000