Cash, Cash Equivalents and Investments (Summary Of Cash, Cash Equivalents And Trading And Available-For-Sale Investments) (Details) (USD $) In Thousands, unless otherwise specified	Nov. 30, 2012	Nov. 30, 2011
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	$ 385,640	$ 301,111
Unrealized Gains	255	221
Unrealized Losses	(4,357)	(6,377)
Fair Value	381,538	294,955
Cash [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	176,201	134,890
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	176,201	134,890
Money Market Funds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	125,591	24,220
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	125,591	24,220
State And Municipal Bond Obligations [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	50,565	84,193
Unrealized Gains	255	221
Unrealized Losses	(2)	(16)
Fair Value	50,818	84,398
Brazilian Mutual Funds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis		15,346
Unrealized Gains		0
Unrealized Losses		0
Fair Value		15,346
Auction Rate Securities - Municipal Bonds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	27,175	27,200
Unrealized Gains	0	0
Unrealized Losses	(3,755)	(4,269)
Fair Value	23,420	22,931
Auction Rate Securities - Student Loans [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	3,500	12,700
Unrealized Gains	0	0
Unrealized Losses	(599)	(2,092)
Fair Value	2,901	10,608
Corporate Bonds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	2,608	2,562
Unrealized Gains	0	0
Unrealized Losses	(1)	0
Fair Value	$ 2,607	$ 2,562