Accounts Receivable (Tables)

3 Months Ended

Oct. 31, 2017

Accounts Receivable Additional Disclosures [Abstract]

Accounts receivable

Accounts receivable consist of the following at:

	October 31, 2017		July 31, 2017
Billed receivables from commercial and international customers	$	66,349,000	71,404,000
Unbilled receivables from commercial and international customers	17,215,000		24,668,000
Billed receivables from the U.S. government and its agencies	14,709,000		18,497,000
Unbilled receivables from the U.S. government and its agencies	17,172,000		11,693,000
Total accounts receivable	115,445,000		126,262,000
Less allowance for doubtful accounts	1,502,000		1,300,000
Accounts receivable, net	$	113,943,000	124,962,000