Cash, Cash Equivalents and Investments (Summary Of Cash, Cash Equivalents And Trading And Available-For-Sale Investments) (Details) - USD ($) $ in Thousands	Feb. 29, 2016	Nov. 30, 2015
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	$ 251,425	$ 241,276
Unrealized Gains	78	30
Unrealized Losses	(12)	(27)
Fair Value	251,491	241,279
State and municipal bond obligations [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	38,217	20,387
Unrealized Gains	78	30
Unrealized Losses	0	0
Fair Value	38,295	20,417
U.S. treasury bonds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	4,110	3,109
Unrealized Gains	0	0
Unrealized Losses	(5)	(15)
Fair Value	4,105	3,094
U.S. government agency bonds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	1,639	1,645
Unrealized Gains	0	0
Unrealized Losses	(1)	(4)
Fair Value	1,638	1,641
Corporate bonds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	3,755	3,756
Unrealized Gains	0	0
Unrealized Losses	(6)	(8)
Fair Value	3,749	3,748
Cash [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	196,422	186,241
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	196,422	186,241
Money market funds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	7,282	26,138
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	$ 7,282	$ 26,138