Lawsuits, Claims, Commitments and Contingencies(Details) - Arbitration filed by Andes Petroleum Ecuador Ltd - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Lawsuits, commitments and contingencies
Proceeds from settlement		$ 1.0
Recovery of amount awarded in settlement amount (as a percent)		60.00%
Percentage of judgment amount claimed	40.00%
Own economic interest (as a percent)	60.00%