Major Customers and Suppliers

12 Months Ended

Dec. 31, 2016

(19) Major Customers and Suppliers

Sales to major customers as a percentage of the respective segment's sales were as follows:



	Year Ended December 31,
	2016		2015		2014
Petroleum
Customer A	15	%	14	%	13	%
Nitrogen Fertilizer
Customer B	10	%	10	%	17	%
Customer C	10	%	14	%	10	%
	20	%	24	%	27	%

The petroleum segment obtained crude oil from one third-party supplier under a long-term supply agreement during 2016, 2015 and 2014. The crude oil purchased from this supplier is governed by a long-term contract. Volume contracted as a percentage of the total crude oil purchases (in barrels) for each of the periods was as follows:



	Year Ended December 31,
	2016		2015		2014
Petroleum
Supplier A	61	%	61	%	67	%