Fair Value Measurements (Fair Value Measurements within the Fair Value Hierarchy of the Financial Assets) (Details) (USD $) In Thousands, unless otherwise specified	Aug. 31, 2012	Nov. 30, 2011
Money Market Funds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of financial assets	$ 125,149	$ 24,220
Money Market Funds [Member] | Level 1 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of financial assets	125,149	24,220
State And Municipal Bond Obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of financial assets	53,882	84,398
State And Municipal Bond Obligations [Member] | Level 2 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of financial assets	53,882	84,398
Brazilian Mutual Funds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of financial assets		15,346
Brazilian Mutual Funds [Member] | Level 1 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of financial assets		15,346
Auction Rate Securities - Municipal Bonds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of financial assets	23,354	22,931
Auction Rate Securities - Municipal Bonds [Member] | Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of financial assets	23,354	22,931
Auction Rate Securities - Student Loans [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of financial assets	7,931	10,608
Auction Rate Securities - Student Loans [Member] | Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of financial assets	7,931	10,608
Corporate Bonds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of financial assets	3,927	2,562
Corporate Bonds [Member] | Level 2 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of financial assets	3,927	2,562
Foreign Exchange Derivatives [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of financial assets	(88)	52
Foreign Exchange Derivatives [Member] | Level 2 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of financial assets	$ (88)	$ 52