Cash, Cash Equivalents and Investments (Summary Of Cash, Cash Equivalents And Trading And Available-For-Sale Investments) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Nov. 30, 2013	Aug. 31, 2014
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	$ 260,406	$ 261,180
Realized Losses	(380)
Unrealized Gains	164	112
Unrealized Losses	(3,989)	0
Fair Value	256,201	261,292
State and municipal bond obligations [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	30,938	18,800
Realized Losses	0
Unrealized Gains	164	112
Unrealized Losses	0	0
Fair Value	31,102	18,912
Auction rate securities - municipal bonds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	27,150
Realized Losses	(380)
Unrealized Gains	0
Unrealized Losses	(3,317)
Fair Value	23,453
Auction rate securities - student loans [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	3,500
Realized Losses	0
Unrealized Gains	0
Unrealized Losses	(672)
Fair Value	2,828
Cash [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	144,305	173,237
Fair Value	144,305	173,237
Money market funds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	54,513	69,143
Fair Value	$ 54,513	$ 69,143