Fair Value (Tables)

12 Months Ended

Dec. 31, 2016

Fair Value Disclosures [Abstract]

Fair Value of Derivatives

The fair value of our derivative financial instruments by level is as follows:

	Fair Value at										Fair Value at
Asset / (Liability (dollars in thousands)	December 31, 2016										December 31, 2015
	Level 1		Level 2			Level 3		Total			Level 1		Level 2			Level 3		Total
Commodity futures natural gas contracts	$	—	$	1,508		$	—	$	1,508		$	—	$	(2,202	)	$	—	$	(2,202	)
Currency contracts	—		—			—		—			—		245			—		245
Interest rate swap	—		(2,035		)	—		(2,035		)	—		(2,378		)	—		(2,378		)
Net derivative asset (liability)	$	—	$	(527	)	$	—	$	(527	)	$	—	$	(4,335	)	$	—	$	(4,335	)

Total Derivative Position Recorded on Balance Sheet

The total derivative position is recorded on the Consolidated Balance Sheets as follows:

Asset / (Liability (dollars in thousands)	December 31, 2016			December 31, 2015
Prepaid and other current assets	$	1,434		$	245
Other assets	74			—
Derivative liability	(1,928		)	(4,265		)
Other long-term liabilities	(107		)	(315		)
Net derivative asset (liability)	$	(527	)	$	(4,335	)

Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block]

Financial instruments carried at cost on the Consolidated Balance Sheets, as well as the related fair values, are as follows:

		December 31, 2016				December 31, 2015
(dollars in thousands)	Fair Value Hierarchy Level	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Term Loan B	Level 2	$	409,000	$	412,068	$	433,400	$	425,815