Fair Value Measurements (Tables)

12 Months Ended

Jul. 31, 2017

Fair Value Measurements [Abstract]

Summary of balance of assets measured at fair value on a recurring basis

(in thousands)	Level 1		Level 2		Level 3		Total
July 31, 2017
Available-for-sale securities:
Marketable securities	$	12,151	$	46,121	$	—	$	58,272
Rafael convertible promissory notes		—		—		6,300		6,300
Total	$	12,151	$	46,121	$	6,300	$	64,572
July 31, 2016
Available-for-sale securities:
Marketable securities	$	12,445	$	40,504	$	—	$	52,949
Rafael convertible promissory notes		—		—		2,000		2,000
Total	$	12,445	$	40,504	$	2,000	$	54,949

Summary of assets measured at fair value on a recurring basis using significant unobservable inputs (Level 3)

Year ended July 31,
(in thousands)	2017		2016		2015
Balance, beginning of period	$	2,000	$	—	$	—
Total gains included in other comprehensive income		2,100		—		—
Purchases		2,200		2,000		—
Balance, end of period	$	6,300	$	2,000	$	—
Change in unrealized gains or losses for the period included in earnings for assets held at the end of the period	$	—	$	—	$	—