Line of Credit (Details) (USD $)	0 Months Ended	12 Months Ended
	Aug. 15, 2011	Nov. 30, 2012
Line of Credit Facility [Line Items]
Line of credit facility, expiration date	August 15, 2016
Letters of credit outstanding amount		$ 300,000
Line of Credit Facility, Term		5 years
Leverage Ratio	3.00
Interest Coverage Ratio	3.00
Revolving Credit Facility Member [Member]
Line of Credit Facility [Line Items]
Unsecured credit facility	150,000,000
Additional borrowing capacity	75,000,000
Line of credit facility outstanding amount		0
Standby letters of credit [Member]
Line of Credit Facility [Line Items]
Additional borrowing capacity	25,000,000
Swing line loans [Member]
Line of Credit Facility [Line Items]
Additional borrowing capacity	20,000,000
Minimum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Commitment Fee Percentage	0.25%
Maximum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Commitment Fee Percentage	0.35%
Base Rate [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.25%
Base Rate [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.75%
Libor Rate [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.25%
Libor Rate [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.75%
One Month Libor Rate [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.00%
Federal Funds Rate [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.50%