Related party transactions (Tables)

12 Months Ended

Dec. 31, 2016

Related Party Transactions [Abstract]

Schedule of related party transactions

A summary of the aforementioned significant related party transactions for the years ended December 31, 2016, 2015 and 2014 is as follows:

	Year Ended December 31,
	2016		2015		2014
Net sales to Glencore	$	1,178,631	$	1,867,711	$	1,262,101
Purchases from Glencore	231,850		393,158		285,167
Purchases from BHH	10,127		46,592		47,804