Accounts Receivable (Tables)

3 Months Ended

Oct. 31, 2011

Accounts Receivable, Net [Abstract]

Accounts receivable detail

	October 31, 2011	July 31, 2011
Billed receivables from commercial customers	$     44,055,000	38,245,000
Billed receivables from the U.S. government and its agencies	22,148,000	22,075,000
Unbilled receivables on contracts-in-progress	9,440,000	11,701,000
Total accounts receivable	75,643,000	72,021,000
Less allowance for doubtful accounts	1,171,000	1,220,000
Accounts receivable, net	$     74,472,000	70,801,000