Cash, Cash Equivalents And Investments (Investments With Continuous Unrealized Losses And Their Related Fair Values) (Details) (USD $) In Thousands, unless otherwise specified	May 31, 2012	Nov. 30, 2011
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less Than 12 Months	$ 18,239	$ 24,585
Unrealized Losses, Less Than 12 Months	(14)	(16)
Fair Value, 12 Months or Greater	31,448	33,539
Unrealized Losses, 12 Months or Greater	(5,527)	(6,361)
Total, Fair Value	49,687	58,124
Total, Unrealized Losses	(5,541)	(6,377)
State And Municipal Bond Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less Than 12 Months	15,613	24,585
Unrealized Losses, Less Than 12 Months	(8)	(16)
Total, Fair Value	15,613	24,585
Total, Unrealized Losses	(8)	(16)
Auction Rate Securities - Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, 12 Months or Greater	23,371	22,931
Unrealized Losses, 12 Months or Greater	(3,804)	(4,269)
Total, Fair Value	23,371	22,931
Total, Unrealized Losses	(3,804)	(4,269)
Auction Rate Securities - Student Loans [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, 12 Months or Greater	8,077	10,608
Unrealized Losses, 12 Months or Greater	(1,723)	(2,092)
Total, Fair Value	8,077	10,608
Total, Unrealized Losses	(1,723)	(2,092)
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less Than 12 Months	2,626
Unrealized Losses, Less Than 12 Months	(6)
Total, Fair Value	2,626
Total, Unrealized Losses	$ (6)