Fair Value Measurements (Details) - USD ($) $ in Thousands		Apr. 30, 2016	Jul. 31, 2015
Assets:
Available-for-sale securities		$ 46,637	$ 40,287
Foreign exchange forward contracts		46	38
Total		$ 46,683	40,325
Liabilities:
Foreign exchange forward contracts			39
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Assets:
Available-for-sale securities	[1]	$ 10,073	$ 6,505
Foreign exchange forward contracts	[1]
Total	[1]	$ 10,073	$ 6,505
Liabilities:
Foreign exchange forward contracts	[1]
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Assets:
Available-for-sale securities	[2]	$ 36,564	$ 33,782
Foreign exchange forward contracts	[2]	46	38
Total	[2]	$ 36,610	33,820
Liabilities:
Foreign exchange forward contracts	[2]		$ 39
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Assets:
Available-for-sale securities	[3]
Foreign exchange forward contracts	[3]
Total	[3]
Liabilities:
Foreign exchange forward contracts	[3]

[1] quoted prices in active markets for identical assets or liabilities

[2] observable inputs other than quoted prices in active markets for identical assets and liabilities

[3] no observable pricing inputs in the market