Company's Segment Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Net sales	$ 77,751	$ 43,281
Total income (loss) from operations	31,548	12,598
Seismic
Segment Reporting Information [Line Items]
Net sales	72,084	37,292
Total income (loss) from operations	33,961	13,961
Non Seismic
Segment Reporting Information [Line Items]
Net sales	5,467	5,788
Total income (loss) from operations	465	993
Corporate
Segment Reporting Information [Line Items]
Net sales	200	201
Total income (loss) from operations	$ (2,878)	$ (2,356)