Cash, Cash Equivalents and Investments (Fair Value of Debt Securities by Contractual Maturity) (Details) - USD ($) $ in Thousands	May 31, 2018	Nov. 30, 2017
Investments and Cash [Abstract]
Due in one year or less	$ 27,247	$ 22,333
Due after one year	19,832	27,812
Total	$ 47,079	$ 50,145