Litigation (Details Textual) (USD $) In Millions, unless otherwise specified	1 Months Ended		6 Months Ended
	Mar. 31, 2011	Jun. 30, 2009 Patent	Jun. 30, 2012	May 31, 2012	Feb. 28, 2011	Sep. 30, 2010	Jan. 31, 2010
Litigation (Textual) [Abstract]
Number of patent apparatus claims contained		4
Minimum distance from coast to make alleged activities not actionable under patent infringement law	more than 12 miles
Principal amount of promissory note				$ 35
Compensatory damages awarded in connection with infringement of patent by Sercel							25.2
Disallowed the award of lost profits associated with infringing products						5.4
Disallowed the award of lost profits associated with certain infringing pre-verdict marine sales						9.0
Awarded for damages, plus interest					10.7
Gain on litigation judgment			12.0
Loss contingency in connection with certain other legal matters			$ 10.0