Cash, Cash Equivalents and Investments (Summary Of Cash, Cash Equivalents And Trading And Available-For-Sale Investments) (Details) - USD ($) $ in Thousands	Nov. 30, 2017	Nov. 30, 2016
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	$ 183,902	$ 249,894
Unrealized Gains	0	0
Unrealized Losses	(293)	(140)
Fair Value	183,609	249,754
State and Municipal Bond Obligations [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	40,458	32,831
Unrealized Gains	0	0
Unrealized Losses	(231)	(107)
Fair Value	40,227	32,724
US Treasury Bonds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	3,517	6,542
Unrealized Gains	0	0
Unrealized Losses	(26)	(29)
Fair Value	3,491	6,513
Corporate Bonds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	6,463	3,485
Unrealized Gains	0	0
Unrealized Losses	(36)	(4)
Fair Value	6,427	3,481
Cash [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	130,547	196,863
Fair Value	130,547	196,863
Money Market Funds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	2,917	10,173
Fair Value	$ 2,917	$ 10,173