Cash, Cash Equivalents And Investments (Summary Of Cash, Cash Equivalents And Trading And Available-For-Sale Investments) (Details) (USD $) In Thousands, unless otherwise specified	May 31, 2012	Nov. 30, 2011
Cash, Cash Equivalents And Investments [Line Items]
Cost Basis	$ 364,945	$ 301,111
Unrealized Gains	292	221
Unrealized Losses	(5,541)	(6,377)
Fair Value	359,696	294,955
Cash [Member]
Cash, Cash Equivalents And Investments [Line Items]
Cost Basis	211,052	134,890
Fair Value	211,052	134,890
Money Market Funds [Member]
Cash, Cash Equivalents And Investments [Line Items]
Cost Basis	29,832	24,220
Fair Value	29,832	24,220
State And Municipal Bond Obligations [Member]
Cash, Cash Equivalents And Investments [Line Items]
Cost Basis	77,931	84,193
Unrealized Gains	292	221
Unrealized Losses	(8)	(16)
Fair Value	78,215	84,398
Brazilian Mutual Funds [Member]
Cash, Cash Equivalents And Investments [Line Items]
Cost Basis		15,346
Fair Value		15,346
Auction Rate Securities - Municipal Bonds [Member]
Cash, Cash Equivalents And Investments [Line Items]
Cost Basis	27,175	27,200
Unrealized Losses	(3,804)	(4,269)
Fair Value	23,371	22,931
Auction Rate Securities - Student Loans [Member]
Cash, Cash Equivalents And Investments [Line Items]
Cost Basis	12,500	12,700
Unrealized Losses	(1,723)	(2,092)
Fair Value	10,777	10,608
Corporate Bonds [Member]
Cash, Cash Equivalents And Investments [Line Items]
Cost Basis	6,455	2,562
Unrealized Losses	(6)
Fair Value	$ 6,449	$ 2,562