Categories of Financial Assets and Financial Liabilities - Financial Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
of which derivative financial instruments	$ 1,968	$ 552	$ 743
Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trade payables	365,788	246,382
Other taxes	44,831	30,463
Employee - related payables	55,874	42,275
Other current liabilities	30,221	15,531
Financial liabilities	85,580	10,428
of which derivative financial instruments	1,968	553
Total liabilities, Fair value	582,294	345,079
Fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trade payables	365,788	246,382
Other taxes	44,831	30,463
Employee - related payables	55,874	42,275
Other current liabilities	30,221	15,531
Financial liabilities	85,580	10,428
of which derivative financial instruments	1,968	553
Total liabilities, Fair value	$ 582,294	$ 345,079