BUSINESS SEGMENT INFORMATION (Details 3) (USD $)	3 Months Ended								12 Months Ended
	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2009	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2009
Business segment financial data
Sales	$ 346,910,000	$ 319,905,000	$ 333,968,000	$ 284,420,000	$ 347,706,000	$ 331,240,000	$ 264,559,000	$ 250,684,000	$ 1,285,203,000.0	$ 1,194,189,000	$ 1,016,657,000
Long-lived assets, net	52,700,000				52,700,000				52,700,000	52,700,000	55,900,000
Minimum percentage of revenue accounted for by no other customer (as a percent)	10.00%								10.00%
United States
Business segment financial data
Sales									705,700,000	774,300,000	666,200,000
Long-lived assets, net	40,700,000				41,000,000				40,700,000	41,000,000	43,700,000
United Kingdom
Business segment financial data
Sales									266,000,000	216,300,000	179,200,000
Long-lived assets, net	9,100,000				9,500,000				9,100,000	9,500,000	10,300,000
Canada
Business segment financial data
Sales									26,500,000	8,100,000	18,500,000
Australia
Business segment financial data
Sales									115,000,000	60,600,000	39,900,000
Middle East
Business segment financial data
Sales									35,500,000	26,900,000	19,300,000
Far East
Business segment financial data
Sales									84,600,000	81,600,000	61,500,000
Other foreign countries
Business segment financial data
Sales									51,900,000	26,400,000	32,100,000
Long-lived assets, net	$ 2,900,000				$ 2,200,000				$ 2,900,000	$ 2,200,000	$ 1,900,000