Commitments and Contingencies - Litigation (Details) - Court of Ouargla Foreign Currency Controls $ in Millions	1 Months Ended		9 Months Ended
	Mar. 31, 2017 USD ($)	Mar. 31, 2011 USD ($)	Sep. 30, 2018 USD ($)
Commitments and Contingencies, Disclosure
Litigation amount as per judgment		$ 23.9
Payment of contract amount in foreign currency	$ 7.5
Payment of contract amount in domestic currency		$ 3.2
Approximate multiplier of the amount at issue for fines and penalties			4
Maximum
Commitments and Contingencies, Disclosure
Potential judgment in excess of accrual			$ 15.9