Business Segments And International Operations (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Nov. 30, 2011	Aug. 31, 2011	May 31, 2011	Feb. 28, 2011	Nov. 30, 2010	Aug. 31, 2010	May 31, 2010	Feb. 28, 2010	Nov. 30, 2011	Nov. 30, 2010	Nov. 30, 2009
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 136,340	$ 128,334	$ 134,684	$ 134,237	$ 145,180	$ 128,737	$ 127,656	$ 127,547	$ 533,595	$ 529,120	$ 494,137
Long-lived assets	66,206				58,207				66,206	58,207
Criteria of major customers, percentage of revenue									10.00%
Criteria for major customers, percentage of long-lived assets									10.00%
United Kingdom [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									60,200	56,000	57,900
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	59,600				54,700				59,600	54,700	55,300
Outside United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 6,600				$ 7,800				$ 6,600	$ 7,800	$ 9,700