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, 2017	Nov. 30, 2016	Aug. 31, 2016	Nov. 30, 2015
Cash, Cash Equivalents and Investments [Line Items]
Cash and Equivalents	$ 144,757	$ 207,036	$ 188,084	$ 212,379
Short-Term Investments	46,559	42,718
State and municipal bond obligations [Member]
Cash, Cash Equivalents and Investments [Line Items]
Cash and Equivalents	1,000	0
Short-Term Investments	36,735	32,724
U.S. treasury bonds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Cash and Equivalents	0	0
Short-Term Investments	3,506	6,513
Corporate bonds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Cash and Equivalents	0	0
Short-Term Investments	6,318	3,481
Cash [Member]
Cash, Cash Equivalents and Investments [Line Items]
Cash and Equivalents	137,911	196,863
Short-Term Investments	0	0
Money market funds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Cash and Equivalents	5,846	10,173
Short-Term Investments	$ 0	$ 0