Litigation (Details) - WesternGeco			1 Months Ended					3 Months Ended					6 Months Ended	9 Months Ended	36 Months Ended
	May 16, 2017 USD ($)	Nov. 25, 2016 USD ($)	May 31, 2014 USD ($)	Apr. 30, 2014 USD ($)	Oct. 31, 2013 USD ($)	Aug. 31, 2012 USD ($)	Jun. 30, 2009 Patent	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2018 USD ($)	Jul. 02, 2015 USD ($)	Nov. 14, 2016 USD ($)	Nov. 13, 2016 USD ($)
Loss Contingencies [Line Items]
Number of patent apparatus claims contained | Patent							4
Pending Litigation
Loss Contingencies [Line Items]
Damages awarded			$ 123,800,000	$ 9,400,000	$ 73,100,000	$ 105,900,000
Reduction in damages award in the case				$ (3,000,000)
Prejudgment interest expense accrued															$ 10,900,000
Amount of appeal bond																$ 65,000,000	$ 120,000,000
Amount of royalty damages paid		$ 20,800,000
Pending Litigation | Lost Royalties
Loss Contingencies [Line Items]
Damages awarded						$ 12,500,000
Pending Litigation | Lost Profits
Loss Contingencies [Line Items]
Damages awarded															$ 93,400,000
Settled Litigation
Loss Contingencies [Line Items]
Damages awarded	$ 5,000,000
Amount of royalty damages paid												$ 625,000
Settled Litigation | Forecast
Loss Contingencies [Line Items]
Amount of royalty damages paid								$ 1,250,000	$ 1,250,000	$ 1,250,000	$ 625,000		$ 1,250,000	$ 3,750,000