Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Assets measured at fair value on a recurring basis, categorized by the level of inputs used in the valuation

measured at fair value on a recurring basis, categorized by the level of inputs used in the valuation, include:

	Derivative Instruments at Fair Value as of December 31, 2017
(Dollars in thousands)	Level 1		Level 2			Level 3		Total
Foreign currency contracts	$	—	$	(396	)	$	—	$	(396	)
Copper derivative contracts	$	—	$	2,016		$	—	$	2,016
Interest rate swap	$	—	$	41		$	—	$	41

	Derivative Instruments at Fair Value as of December 31, 2016
(Dollars in thousands)	Level 1		Level 2			Level 3		Total
Foreign currency contracts	$	—	$	(170	)	$	—	$	(170	)
Copper derivative contracts	$	—	$	1,277		$	—	$	1,277