Cash, Cash Equivalents and Investments (Summary Of Cash, Cash Equivalents And Trading And Available-For-Sale Investments) (Details) - USD ($) $ in Thousands	Aug. 31, 2015	Nov. 30, 2014
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	$ 218,270	$ 283,182
Unrealized Gains	52	86
Unrealized Losses	(18)	0
Fair Value	218,304	283,268
State and municipal bond obligations [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	29,157	20,100
Unrealized Gains	52	86
Unrealized Losses	(18)	0
Fair Value	29,191	20,186
Cash [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	163,248	195,189
Fair Value	163,248	195,189
Money market funds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	25,865	67,893
Fair Value	$ 25,865	$ 67,893