Property Plant and Equipment (Detail) (USD $)					12 Months Ended				12 Months Ended				12 Months Ended			12 Months Ended				12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 Land, building and other	Sep. 30, 2012 Land, building and other	Sep. 30, 2013 Land, building and other Minimum	Sep. 30, 2012 Land, building and other Maximum	Sep. 30, 2013 Recording Equipment	Sep. 30, 2012 Recording Equipment	Sep. 30, 2013 Recording Equipment Minimum	Sep. 30, 2012 Recording Equipment Maximum	Sep. 30, 2013 Line Clearing Equipment	Sep. 30, 2012 Line Clearing Equipment	Sep. 30, 2013 Line Clearing Equipment Minimum	Sep. 30, 2013 Vibrator Energy Sources	Sep. 30, 2012 Vibrator Energy Sources	Sep. 30, 2013 Vibrator Energy Sources Minimum	Sep. 30, 2012 Vibrator Energy Sources Maximum	Sep. 30, 2013 Vehicles	Sep. 30, 2012 Vehicles	Sep. 30, 2013 Vehicles Minimum	Sep. 30, 2012 Vehicles Maximum	Sep. 30, 2013 Other		Sep. 30, 2012 Other
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 325,464,000	$ 326,030,000	$ 10,822,000	$ 8,641,000			$ 197,134,000	$ 206,642,000			$ 937,000	$ 913,000		$ 80,309,000	$ 76,813,000			$ 35,623,000	$ 32,429,000			$ 639,000	[1]	$ 592,000	[1]
Less accumulated depreciation	(152,231,000)	(164,634,000)
Net property, plant and equipment	$ 173,233,000	$ 161,396,000
Useful Lives					3 years	40 years			5 years	10 years			5 years			5 years	15 years			1 year 6 months	10 years

[1] Other represents accumulated costs associated with equipment fabrication and modification not yet completed.