Company's Segment Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Segment Reporting Information [Line Items]
Net sales	$ 78,148	$ 55,201	$ 232,319	$ 154,715
Total income (loss) from operations	24,991	15,601	82,095	44,671
Seismic
Segment Reporting Information [Line Items]
Net sales	71,261	47,919	213,103	133,928
Total income (loss) from operations	26,932	16,840	88,735	48,518
Non Seismic
Segment Reporting Information [Line Items]
Net sales	6,683	7,082	18,594	20,186
Total income (loss) from operations	972	1,146	2,329	3,464
Corporate
Segment Reporting Information [Line Items]
Net sales	204	200	622	601
Total income (loss) from operations	$ (2,913)	$ (2,385)	$ (8,969)	$ (7,311)