Line Of Credit (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	May 31, 2012
Line of Credit Facility [Line Items]
Unsecured credit facility	$ 150.0
Additional borrowing capacity	75.0
Line of credit facility outstanding amount	0
Letters of credit outstanding amount	0.2
Standby Letters Of Credit [Member]
Line of Credit Facility [Line Items]
Additional borrowing capacity	25.0
Swing Line Loans [Member]
Line of Credit Facility [Line Items]
Additional borrowing capacity	$ 20.0