Fair Value (Tables)

6 Months Ended

Jun. 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)	June 30, 2016										December 31, 2015
	Level 1		Level 2			Level 3		Total			Level 1		Level 2			Level 3		Total
Commodity futures natural gas contracts	$	—	$	86		$	—	$	86		$	—	$	(2,202	)	$	—	$	(2,202	)
Currency contracts	—		(143		)	—		(143		)	—		245			—		245
Interest rate swap	—		(6,189		)	—		(6,189		)	—		(2,378		)	—		(2,378		)
Net derivative asset (liability)	$	—	$	(6,246	)	$	—	$	(6,246	)	$	—	$	(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)	June 30, 2016			December 31, 2015
Prepaid and other current assets	$	87		$	245
Other assets	1			—
Derivative liability	(2,529		)	(4,265		)
Other long-term liabilities	(3,805		)	(315		)
Net derivative asset (liability)	$	(6,246	)	$	(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:

		June 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	$	421,200	$	418,568	$	433,400	$	425,815