Cash, Cash Equivalents and Investments (Investments with Continuous Unrealized Losses and Their Related Fair Values) (Details) (USD $) In Thousands, unless otherwise specified	Nov. 30, 2012	Nov. 30, 2011
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less Than 12 Months	$ 8,425	$ 24,585
Unrealized Losses, Less Than 12 Months	(2)	(16)
Fair Value, 12 Months or Greater	26,793	33,539
Unrealized Losses, 12 Months or Greater	(4,355)	(6,361)
Total, Fair Value	35,218	58,124
Total, Unrealized Losses	(4,357)	(6,377)
State And Municipal Bond Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less Than 12 Months	5,818	24,585
Unrealized Losses, Less Than 12 Months	(1)	(16)
Fair Value, 12 Months or Greater	472	0
Unrealized Losses, 12 Months or Greater	(1)	0
Total, Fair Value	6,290	24,585
Total, Unrealized Losses	(2)	(16)
Auction Rate Securities - Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less Than 12 Months	0	0
Unrealized Losses, Less Than 12 Months	0	0
Fair Value, 12 Months or Greater	23,420	22,931
Unrealized Losses, 12 Months or Greater	(3,755)	(4,269)
Total, Fair Value	23,420	22,931
Total, Unrealized Losses	(3,755)	(4,269)
Auction Rate Securities - Student Loans [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less Than 12 Months	0	0
Unrealized Losses, Less Than 12 Months	0	0
Fair Value, 12 Months or Greater	2,901	10,608
Unrealized Losses, 12 Months or Greater	(599)	(2,092)
Total, Fair Value	2,901	10,608
Total, Unrealized Losses	(599)	(2,092)
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less Than 12 Months	2,607
Unrealized Losses, Less Than 12 Months	(1)
Fair Value, 12 Months or Greater	0
Unrealized Losses, 12 Months or Greater	0
Total, Fair Value	2,607
Total, Unrealized Losses	$ (1)