Property, Plant and Equipment (Tables)

6 Months Ended

Jun. 30, 2018

Property, Plant and Equipment [Abstract]

Schedule of Property, Plant and Equipment

	June 30, 2018			December 31, 2017
(Dollars in thousands)
Land and buildings	$	137,987		$	136,918
Machinery and equipment		740,413			720,175
Leasehold improvements and others		12,281			12,192
Construction in progress		64,397			58,753
		955,078			928,038
Accumulated depreciation		(423,733	)		(391,352	)
Property, plant and equipment, net	$	531,345		$	536,686