Cash, Cash Equivalents And Investments (Narrative) (Details) (USD $)	May 31, 2012	Nov. 30, 2011
Cash, Cash Equivalents And Investments [Line Items]
Long-term Investments	$ 31,448,000	$ 33,539,000
Short-term Investments	86,364,000	100,321,000
Cash and short-term investments balance	328,248,000	261,416,000
Other accrued expenses	41,126,000	35,728,000
State And Municipal Bond Obligations [Member]
Cash, Cash Equivalents And Investments [Line Items]
Short-term Investments	77,215,000	82,413,000
Other accrued expenses	2,000,000
Auction Rate Securities [Member]
Cash, Cash Equivalents And Investments [Line Items]
Long-term Investments	34,148,000	33,539,000
Unrealized losses	5,500,000	6,400,000
Auction Rate Securities - Municipal Bonds [Member]
Cash, Cash Equivalents And Investments [Line Items]
Long-term Investments	23,371,000	22,931,000
Auction Rate Securities - Student Loans [Member]
Cash, Cash Equivalents And Investments [Line Items]
Long-term Investments	8,077,000	10,608,000
Short-term Investments	$ 2,700,000