Cash, Cash Equivalents and Investments (Fair Value of Debt Securities by Contractual Maturity) (Details) (USD $) In Thousands, unless otherwise specified					6 Months Ended
	May 31, 2014		Nov. 30, 2013		May 31, 2014 Minimum [Member]	May 31, 2014 Maximum [Member]
Cash, Cash Equivalents and Investments [Line Items]
Due in one year or less	$ 39,943	[1]	$ 42,198	[1]
Due after one year	9,718	[2]	15,185	[2]
Total	$ 49,661		$ 57,383
Remaining contractual maturity of investments					10 years	29 years

[1] Includes ARS which are tendered for interest-rate setting purposes periodically throughout the year. Beginning in February 2008, auctions for these securities began to fail, and therefore these investments currently lack short-term liquidity. The remaining contractual maturities of these securities range from 10 to 29 years.

[2] Includes state and municipal bond obligations, which are securities representing investments available for current operations and are classified as current in the consolidated balance sheets.