Debt (Details) (USD $)	9 Months Ended	12 Months Ended
	Aug. 28, 2011	Nov. 30, 2011	Nov. 30, 2010
Debt Instrument [Line Items]
Long-term debt	$ 32,642,000		$ 31,148,000
Long-term debt, current portion	(8,471,000)		(7,724,000)
Long-term debt, less current portion	24,171,000		23,424,000
Covenant requirement, minimum net worth required	375,500,000
Covenant requirement, percentage of net income	50.00%
Covenant requirement, percentage of proceeds from equity issued after November 30, 2008	75.00%
Covenant compliance, net worth exceeded covenant amount	123,982,000
Covenant requirement, maximum consolidated leverage ratio	2
Covenant compliance, consolidated leverage ratio at period end	1.12
Qualifying tangible assets to funded indebtedness ratio	5.78
Minimum fixed charge coverage ratio required	1.10	1.35
Minimum fixed charge coverage ratio required for next fiscal year and thereafter	1.50
Fixed charge coverage ratio at period end	0.91
Maximum dividend declaration per quarter	$ 0.30
Covenant requirement, prior maximum leverage ratio required	2.5
Domestic Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Revolving credit facility amount	100,000,000
Number of banks providing revolving credit facility	6
Amount utilized for standby letters of credit	17,052,000
Revolving credit facility amount available	82,948,000
Floating interest rate basis	LIBOR
Domestic Revolving Credit Facility [Member] | Minimum [Member]
Debt Instrument [Line Items]
Interest rate basis spread	2.75%
Domestic Revolving Credit Facility [Member] | Maximum [Member]
Debt Instrument [Line Items]
Interest rate basis spread	3.75%
Foreign Subsidiaries Revolving Credit Facilities [Member]
Debt Instrument [Line Items]
Revolving credit facility amount	34,771,000
Borrowings outstandng	121,000
Fixed-rate Notes [Member]
Debt Instrument [Line Items]
Long-term debt	16,942,000		15,448,000
Fixed interest rate	4.25%
Annual principal installments	8,471
Long-term debt, fair value	17,438,000		16,445,000
Variable-rate Industrial Development Bonds [Member]
Debt Instrument [Line Items]
Floating interest rate basis	SIFMA
Interest rate basis spread	0.20%
Long-term debt	15,700,000		15,700,000
Long-term debt, fair value	15,700,000		15,700,000
Variable-rate Industrial Development Bonds Payable in 2016 [Member]
Debt Instrument [Line Items]
Long-term debt	7,200,000		7,200,000
Interest rate at period end	0.40%
Variable-rate Industrial Development Bonds Payable in 2021 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 8,500,000		$ 8,500,000
Interest rate at period end	0.40%