Summary of Company's Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Sales	$ 101,348	$ 77,751
Total income (loss) from operations	35,667	31,548
Seismic
Segment Reporting Information [Line Items]
Sales	95,227	72,084
Total income (loss) from operations	38,543	33,961
Non-Seismic
Segment Reporting Information [Line Items]
Sales	5,912	5,467
Total income (loss) from operations	774	465
Corporate
Segment Reporting Information [Line Items]
Sales	209	200
Total income (loss) from operations	$ (3,650)	$ (2,878)