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	Feb. 28, 2018	Nov. 30, 2017	Feb. 28, 2017	Nov. 30, 2016
Cash, Cash Equivalents and Investments [Line Items]
Cash and Equivalents	$ 117,111	$ 133,464	$ 226,907	$ 207,036
Short-Term Investments	50,386	50,145
State and municipal bond obligations [Member]
Cash, Cash Equivalents and Investments [Line Items]
Cash and Equivalents	0	0
Short-Term Investments	35,354	40,227
U.S. treasury bonds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Cash and Equivalents	0	0
Short-Term Investments	7,662	3,491
Corporate bonds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Cash and Equivalents	0	0
Short-Term Investments	7,370	6,427
Cash [Member]
Cash, Cash Equivalents and Investments [Line Items]
Cash and Equivalents	113,420	130,547
Short-Term Investments	0	0
Money market funds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Cash and Equivalents	3,691	2,917
Short-Term Investments	$ 0	$ 0