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	May 31, 2014
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	$ 260,406	$ 255,191
Realized Losses	(380)
Unrealized Gains	164	135
Unrealized Losses	(3,989)	(3,694)
Fair Value	256,201	251,632
State and municipal bond obligations [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	30,938	24,470
Realized Losses	0
Unrealized Gains	164	135
Unrealized Losses	0	0
Fair Value	31,102	24,605
Auction rate securities - municipal bonds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	27,150	25,250
Realized Losses	(380)
Unrealized Gains	0	0
Unrealized Losses	(3,317)	(3,063)
Fair Value	23,453	22,187
Auction rate securities - student loans [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	3,500	3,500
Realized Losses	0
Unrealized Gains	0	0
Unrealized Losses	(672)	(631)
Fair Value	2,828	2,869
Cash [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	144,305	127,279
Fair Value	144,305	127,279
Money market funds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	54,513	74,692
Fair Value	$ 54,513	$ 74,692