Cash, Cash Equivalents and Investments (Narrative) (Details) (USD $)	3 Months Ended	9 Months Ended
	Aug. 31, 2014	Aug. 31, 2014	Aug. 31, 2013	Nov. 30, 2013
Cash, Cash Equivalents and Investments [Line Items]
Redemptions and sales of auction rate securities		$ 26,196,000	$ 25,000
Loss on sale of auction rate securities	2,600,000
Investments in auction rate securities	0	0		24,761,000
Unrealized Losses	0	0		3,989,000
Auction Rate Securities [Member]
Cash, Cash Equivalents and Investments [Line Items]
Investments in auction rate securities				24,800,000
Unrealized Losses				$ 4,000,000
Percentage of par value to be received after renouncing claim				80.00%
Percentage of par to be received if insurance rights retained				65.00%
Percentage of par value received on investment				80.00%