Cash, Cash Equivalents and Investments (Investments with Continuous Unrealized Losses and Their Related Fair Values) (Details) (USD $) In Thousands, unless otherwise specified	May 31, 2013	Nov. 30, 2012
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less Than 12 Months	$ 0	$ 8,425
Unrealized Losses, Less Than 12 Months	0	(2)
Fair Value, 12 Months or Greater	26,500	26,793
Unrealized Losses, 12 Months or Greater	(4,150)	(4,355)
Total, Fair Value	26,500	35,218
Total, Unrealized Losses	(4,150)	(4,357)
State and municipal bond obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less Than 12 Months		5,818
Unrealized Losses, Less Than 12 Months		(1)
Fair Value, 12 Months or Greater		472
Unrealized Losses, 12 Months or Greater		(1)
Total, Fair Value		6,290
Total, Unrealized Losses		(2)
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	23,562	23,420
Unrealized Losses, 12 Months or Greater	(3,588)	(3,755)
Total, Fair Value	23,562	23,420
Total, Unrealized Losses	(3,588)	(3,755)
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	2,938	2,901
Unrealized Losses, 12 Months or Greater	(562)	(599)
Total, Fair Value	2,938	2,901
Total, Unrealized Losses	(562)	(599)
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)