Cash, Cash Equivalents and Investments (Summary of Cash, Cash Equivalents and Trading and Available-for-sale Investments by Balance Sheet Classification) (Details) - USD ($) $ in Thousands	Aug. 31, 2018	Nov. 30, 2017	Aug. 31, 2017	Nov. 30, 2016
Cash, Cash Equivalents and Investments [Line Items]
Cash and Equivalents	$ 98,697	$ 133,464	$ 144,757	$ 207,036
Short-Term Investments	39,184	50,145
State and municipal bond obligations
Cash, Cash Equivalents and Investments [Line Items]
Cash and Equivalents	0	0
Short-Term Investments	24,224	40,227
U.S. treasury bonds
Cash, Cash Equivalents and Investments [Line Items]
Cash and Equivalents	0	0
Short-Term Investments	6,690	3,491
Corporate bonds
Cash, Cash Equivalents and Investments [Line Items]
Cash and Equivalents	0	0
Short-Term Investments	8,270	6,427
Cash
Cash, Cash Equivalents and Investments [Line Items]
Cash and Equivalents	92,827	130,547
Short-Term Investments	0	0
Money market funds
Cash, Cash Equivalents and Investments [Line Items]
Cash and Equivalents	5,870	2,917
Short-Term Investments	$ 0	$ 0