Debt Securities (Tables)

3 Months Ended

Oct. 31, 2018

Debt Securities [Abstract]

Summary of marketable debt securities

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(in thousands)
Available-for-sale debt securities:
October 31, 2018:
U.S. Treasury notes	$	1,697	$	—	$	(2	)	$	1,695
Municipal bonds		543		—		(1	)		542
Total	$	2,240	$	—	$	(3	)	$	2,237
July 31, 2018:
Certificates of deposit*	$	3,032	$	—	$	—		$	3,032
U.S. Treasury notes		1,693		—		(1	)		1,692
Municipal bonds		888		—		—			888
Total	$	5,613	$	—	$	(1	)	$	5,612

* Each of the Company’s certificates of deposit has a CUSIP, was purchased in the secondary market through a broker, and may be sold in the secondary market.

Summary of available-for-sale debt securities

	Fair Value
	(in thousands)
Within one year	$	2,237
After one year through five years		—
After five years through ten years		—
After ten years		—
Total	$	2,237

Summary of available-for-sale securities, unrealized loss position

	Unrealized Losses		Fair Value
	(in thousands)
October 31, 2018:
U.S. Treasury notes	$	2	$	1,695
Municipal bonds		1		542
Total	$	3	$	2,237
July 31, 2018:
U.S. Treasury notes	$	1	$	1,692