Derivative Instruments (Tables)

9 Months Ended

Sep. 30, 2018

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Derivative Instruments in Statement of Financial Position, Fair Value

The fair value of all derivatives is recorded as assets or liabilities on a gross basis in our Condensed Consolidated Balance Sheets. As of September 30, 2018 and December 31, 2017, respectively, the fair value of our derivatives and their respective balance sheet locations are presented in the following table:

	Asset Derivatives			Liability Derivatives
	Location	Fair  Value		Location	Fair  Value
As of September 30, 2018	(Dollars in thousands)
Derivatives designated as cash flow hedges:
Commodity derivative contracts	Prepaid and other current assets	$	18,024	Other accrued liabilities	$	—
	Other long-term assets	23,950		Other long-term obligations	—
Total fair value		$	41,974		$	—
As of December 31, 2017
Derivatives designated as cash flow hedges:
Commodity derivative contracts	Prepaid and other current assets	$	2,518	Other accrued liabilities	$	—
	Other long-term assets	2,808		Other long-term obligations	581
Total fair value		$	5,326		$	581

The realized (gains) losses on commodity derivatives remain in Other Comprehensive Income until they are recognized in the Statements of Operations when the hedged item impacts earnings, which is when the finished product is sold. With respect to the inputs used to determine the fair value, we use observable, quoted market rates that are determined by active markets and, therefore, classify the contracts as "Level 2".

	Asset Derivatives			Liability Derivatives
	Location	Fair  Value		Location	Fair  Value
As of September 30, 2018	(Dollars in Thousands)
Derivatives not designated as hedges:
Foreign currency derivatives	Prepaid and other current assets	$	30	Other current liabilities	$	9
As of December 31, 2017
Derivatives not designated as hedges:
Foreign currency derivatives	Prepaid and other current assets	$	9	Other current liabilities	$	90

Schedule of Derivatives Instruments Statements of Financial Performance and Financial Position, Location

		Amount of (Gain)/Loss Recognized
	Location of (Gain)/Loss Recognized in the Consolidated Statement of Operations	For the Three Months Ended September 30,
		2018		2017
Derivatives designated as cash flow hedges:		(Dollars in thousands)
Commodity contract hedges	Cost of sales	421		—
Derivatives not designated as hedges:
Foreign currency derivatives	Cost of sales, Other expense/(income)	(159	)	(266	)

		Amount of (Gain)/Loss Recognized
	Location of (Gain)/Loss Recognized in the Consolidated Statement of Operations	For the Nine Months Ended September 30,
		2018		2017
Derivatives designated as cash flow hedges:		(Dollars in thousands)
Commodity contract hedges	Cost of sales	$	421	—
Derivatives not designated as hedges:
Foreign currency derivatives	Cost of sales, Other expense/(income)	$	137	$	(1,108	)