Cash, Cash Equivalents and Investments (Summary Of Cash, Cash Equivalents And Trading And Available-For-Sale Investments) (Details) - USD ($) $ in Thousands	Nov. 30, 2016	Nov. 30, 2015
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	$ 249,894	$ 241,276
Unrealized Gains	0	30
Unrealized Losses	(140)	(27)
Fair Value	249,754	241,279
State and Municipal Bond Obligations [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	32,831	20,387
Unrealized Gains	0	30
Unrealized Losses	(107)	0
Fair Value	32,724	20,417
US Treasury Bonds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	6,542	3,109
Unrealized Gains	0	0
Unrealized Losses	(29)	(15)
Fair Value	6,513	3,094
US Government Agency Bonds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis		1,645
Unrealized Gains		0
Unrealized Losses		(4)
Fair Value		1,641
Corporate Bonds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	3,485	3,756
Unrealized Gains	0	0
Unrealized Losses	(4)	(8)
Fair Value	3,481	3,748
Cash [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	196,863	186,241
Fair Value	196,863	186,241
Money Market Funds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	10,173	26,138
Fair Value	$ 10,173	$ 26,138