Fair Value (Tables)

9 Months Ended

Sep. 30, 2016

Fair Value Disclosures [Abstract]

Fair Value Measurements, Recurring and Nonrecurring [Table Text Block]

	Fair Value at										Fair Value at
Asset / (Liability) (dollars in thousands)	September 30, 2016										December 31, 2015
	Level 1		Level 2			Level 3		Total			Level 1		Level 2			Level 3		Total
Commodity futures natural gas contracts	$	—	$	103		$	—	$	103		$	—	$	(2,202	)	$	—	$	(2,202	)
Currency contracts	—		(36		)	—		(36		)	—		245			—		245
Interest rate swap	—		(5,416		)	—		(5,416		)	—		(2,378		)	—		(2,378		)
Net derivative asset (liability)	$	—	$	(5,349	)	$	—	$	(5,349	)	$	—	$	(4,335	)	$	—	$	(4,335	)

Fair Value, by Balance Sheet Grouping [Table Text Block]

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

Asset / (Liability) (dollars in thousands)	September 30, 2016			December 31, 2015
Prepaid and other current assets	$	135		$	245
Derivative liability	(2,293		)	(4,265		)
Other long-term liabilities	(3,191		)	(315		)
Net derivative asset (liability)	$	(5,349	)	$	(4,335	)

Fair Value Disclosures, Carrying Value and Estimated Fair Value of Debt Instruments [Table Text Block]

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

		September 30, 2016				December 31, 2015
(dollars in thousands)	Fair Value Hierarchy Level	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Term Loan B	Level 2	$	415,100	$	416,138	$	433,400	$	425,815