Supplemental Financial Statement Data (Narrative) (Details) (USD $)	3 Months Ended								12 Months Ended
	Nov. 30, 2012	Aug. 31, 2012	May 31, 2012	Feb. 29, 2012	Nov. 30, 2011	Aug. 31, 2011	May 31, 2011	Feb. 28, 2011	Nov. 30, 2012	Nov. 30, 2011	Nov. 30, 2010
Supplemental Financial Statement Data [Abstract]
Dividends paid per share (usd per share)	$ 0.31	$ 0.31	$ 0.31	$ 0.31	$ 0.28	$ 0.28	$ 0.28	$ 0.28	$ 1.24	$ 1.12	$ 1.04