Cash, Cash Equivalents and Investments (Summary Of Cash, Cash Equivalents And Trading And Available-For-Sale Investments) (Details) - USD ($) $ in Thousands	May 31, 2016	Nov. 30, 2015
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	$ 229,109	$ 241,276
Unrealized Gains	6	30
Unrealized Losses	(6)	(27)
Fair Value	229,109	241,279
State and municipal bond obligations [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	39,584	20,387
Unrealized Gains	3	30
Unrealized Losses	0	0
Fair Value	39,587	20,417
U.S. treasury bonds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	4,658	3,109
Unrealized Gains	0	0
Unrealized Losses	(6)	(15)
Fair Value	4,652	3,094
U.S. government agency bonds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	1,633	1,645
Unrealized Gains	0	0
Unrealized Losses	0	(4)
Fair Value	1,633	1,641
Corporate bonds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	3,501	3,756
Unrealized Gains	3	0
Unrealized Losses	0	(8)
Fair Value	3,504	3,748
Cash [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	174,198	186,241
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	174,198	186,241
Money market funds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	5,535	26,138
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	$ 5,535	$ 26,138