Revenue Recognition (Disaggregation of Revenue) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jan. 31, 2022	Jan. 31, 2021	Jan. 31, 2022	Jan. 31, 2021
Disaggregation of Revenue [Line Items]
Net sales	$ 120,381,000	$ 161,292,000	$ 237,140,000	$ 296,510,000
Point in time
Disaggregation of Revenue [Line Items]
Net sales	47,799,000	63,670,000	88,562,000	116,372,000
Over time
Disaggregation of Revenue [Line Items]
Net sales	72,582,000	97,622,000	148,578,000	180,138,000
Firm fixed-price
Disaggregation of Revenue [Line Items]
Net sales	113,367,000	125,218,000	222,469,000	238,862,000
Cost reimbursable
Disaggregation of Revenue [Line Items]
Net sales	7,014,000	36,074,000	14,671,000	57,648,000
U.S. government
Disaggregation of Revenue [Line Items]
Net sales	32,551,000	71,344,000	67,720,000	115,234,000
Domestic
Disaggregation of Revenue [Line Items]
Net sales	57,320,000	54,643,000	113,875,000	111,357,000
Total United States
Disaggregation of Revenue [Line Items]
Net sales	89,871,000	125,987,000	181,595,000	226,591,000
International
Disaggregation of Revenue [Line Items]
Net sales	30,510,000	35,305,000	55,545,000	69,919,000
Commercial Solutions
Disaggregation of Revenue [Line Items]
Net sales	81,277,000	87,825,000	160,211,000	169,627,000
Commercial Solutions | Point in time
Disaggregation of Revenue [Line Items]
Net sales	28,597,000	37,135,000	52,797,000	66,806,000
Commercial Solutions | Over time
Disaggregation of Revenue [Line Items]
Net sales	52,680,000	50,690,000	107,414,000	102,821,000
Commercial Solutions | Firm fixed-price
Disaggregation of Revenue [Line Items]
Net sales	81,155,000	87,144,000	159,875,000	168,132,000
Commercial Solutions | Cost reimbursable
Disaggregation of Revenue [Line Items]
Net sales	122,000	681,000	336,000	1,495,000
Commercial Solutions | U.S. government
Disaggregation of Revenue [Line Items]
Net sales	12,254,000	16,846,000	23,288,000	26,304,000
Commercial Solutions | Domestic
Disaggregation of Revenue [Line Items]
Net sales	50,563,000	47,959,000	101,783,000	97,259,000
Commercial Solutions | Total United States
Disaggregation of Revenue [Line Items]
Net sales	62,817,000	64,805,000	125,071,000	123,563,000
Commercial Solutions | International
Disaggregation of Revenue [Line Items]
Net sales	18,460,000	23,020,000	35,140,000	46,064,000
Government Solutions
Disaggregation of Revenue [Line Items]
Net sales	39,104,000	73,467,000	76,929,000	126,883,000
Government Solutions | Point in time
Disaggregation of Revenue [Line Items]
Net sales	19,202,000	26,535,000	35,765,000	49,566,000
Government Solutions | Over time
Disaggregation of Revenue [Line Items]
Net sales	19,902,000	46,932,000	41,164,000	77,317,000
Government Solutions | Firm fixed-price
Disaggregation of Revenue [Line Items]
Net sales	32,212,000	38,074,000	62,594,000	70,730,000
Government Solutions | Cost reimbursable
Disaggregation of Revenue [Line Items]
Net sales	6,892,000	35,393,000	14,335,000	56,153,000
Government Solutions | U.S. government
Disaggregation of Revenue [Line Items]
Net sales	20,297,000	54,498,000	44,432,000	88,930,000
Government Solutions | Domestic
Disaggregation of Revenue [Line Items]
Net sales	6,757,000	6,684,000	12,092,000	14,098,000
Government Solutions | Total United States
Disaggregation of Revenue [Line Items]
Net sales	27,054,000	61,182,000	56,524,000	103,028,000
Government Solutions | International
Disaggregation of Revenue [Line Items]
Net sales	$ 12,050,000	$ 12,285,000	$ 20,405,000	$ 23,855,000