Description of Business and Presentation of Financials Statements - Impact of Adoption on Income Statement (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2018		Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Cost of products sold	$ 3,752,234	[1]	$ 2,888,549	$ 10,695,275	$ 8,283,183
Operating expenses	317,196	[1]	322,277	933,699	946,264
Selling, general and administrative expenses	71,130		68,252	204,469	185,303
Other, net	$ 741		1,153	$ 3,451	2,550
Prior to Adoption
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Cost of products sold			2,888,530		8,283,127
Operating expenses			321,668		944,437
Selling, general and administrative expenses			68,013		184,659
Other, net			286		23
Restatement Adjustment | Accounting Standards Update 2017-07
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Cost of products sold			19		56
Operating expenses			609		1,827
Selling, general and administrative expenses			239		644
Other, net			$ 867		$ 2,527

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