Related Party Transactions (Details) - Unconsolidated Affiliates - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Related Party Transaction [Line Items]
Sales to unconsolidated affiliates	$ 11,033	$ 9,255	$ 15,638	$ 16,444
Purchases from unconsolidated affiliates	57,059	$ 55,949	125,975	$ 96,519
Receivable from related parties	3,239		3,239		$ 2,406
Payable to related parties	$ 56,753		$ 56,753		$ 55,801

Amount for accounts payable to related parties.

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