Line of Credit (Narrative) (Details) (USD $)	3 Months Ended
	Feb. 28, 2014
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Unsecured credit facility	$ 150,000,000.0
Additional borrowing capacity	75,000,000.0
Line of credit facility outstanding amount	0
Standby letters of credit [Member]
Line of Credit Facility [Line Items]
Additional borrowing capacity	25,000,000.0
Letters of credit outstanding amount	800,000
Swing line loans [Member]
Line of Credit Facility [Line Items]
Additional borrowing capacity	$ 20,000,000.0