Cash, Cash Equivalents and Investments (Summary of Cash, Cash Equivalents and Trading and Available-for-sale Investments by Balance Sheet Classification) (Details) (USD $) In Thousands, unless otherwise specified	Feb. 28, 2013	Nov. 30, 2012	Feb. 29, 2012	Nov. 30, 2011
Cash, Cash Equivalents and Investments [Line Items]
Cash and Equivalents	$ 279,217	$ 301,792	$ 231,695	$ 161,095
Short-Term Investments	42,158	53,425
Long-Term Investments	26,442	26,321
Cash [Member]
Cash, Cash Equivalents and Investments [Line Items]
Cash and Equivalents	186,961	176,201
Short-Term Investments	0	0
Long-Term Investments	0	0
Money market funds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Cash and Equivalents	92,256	125,591
Short-Term Investments	0	0
Long-Term Investments	0	0
State and municipal bond obligations [Member]
Cash, Cash Equivalents and Investments [Line Items]
Cash and Equivalents	0	0
Short-Term Investments	42,158	50,818
Long-Term Investments	0	0
Auction rate securities - municipal bonds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Cash and Equivalents	0	0
Short-Term Investments	0	0
Long-Term Investments	23,515	23,420
Auction rate securities - student loans [Member]
Cash, Cash Equivalents and Investments [Line Items]
Cash and Equivalents	0	0
Short-Term Investments	0	0
Long-Term Investments	2,927	2,901
Corporate bonds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Cash and Equivalents	0	0
Short-Term Investments	0	2,607
Long-Term Investments	$ 0	$ 0