Cash And Investments (Summary Of Cash, Cash Equivalents And Trading And Available-For-Sale Investments) (Details) (USD $) In Thousands, unless otherwise specified	Nov. 30, 2011	Nov. 30, 2010
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	$ 301,111	$ 368,420
Cash, Cash Equivalents, and Short-term Investments	261,416	322,396
Unrealized Gains	221	207
Unrealized Losses	(6,377)	(6,588)
Fair Value	294,955	362,039
Cash [Member]
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	134,890	154,718
Fair Value	134,890	154,718
Money Market Funds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	24,220	122,415
Fair Value	24,220	122,415
State And Municipal Bond Obligations [Member]
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	84,193	25,484
Unrealized Gains	221	207
Unrealized Losses	(16)	(10)
Fair Value	84,398	25,681
Brazilian Mutual Funds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	15,346
Fair Value	15,346
U.S. Government And Agency Securities [Member]
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis		10,000
Fair Value		10,000
Auction Rate Securities - Municipal Bonds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	27,200	27,200
Unrealized Losses	(4,269)	(3,560)
Fair Value	22,931	23,640
Auction Rate Securities - Student Loans [Member]
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	12,700	19,000
Unrealized Losses	(2,092)	(2,997)
Fair Value	10,608	16,003
Corporate Bonds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	2,562	9,418
Unrealized Losses		(21)
Fair Value	2,562	9,397
Certificates Of Deposit [Member]
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis		185
Fair Value		$ 185