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Commitments and Contingencies (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]      
Beginning Balance $ 22,604 $ 18,548 $ 15,946
Accretion 4,070 2,812 2,292
Payments made (3,111) (160) (159)
Currency translation adjustments (1,820) 1,404 469
Ending Balance $ 21,743 $ 22,604 $ 18,548