Property, Plant and Equipment (Tables)

3 Months Ended

Mar. 31, 2018

Property, Plant and Equipment [Abstract]

Schedule of Property, Plant and Equipment

	March 31, 2018			December 31, 2017
(Dollars in thousands)
Land and buildings	$	144,325		$	136,918
Machinery and equipment		755,148			720,175
Leasehold improvements and others		12,447			12,192
Construction in progress		61,230			58,753
		973,150			928,038
Accumulated depreciation		(420,998	)		(391,352	)
Property, plant and equipment, net	$	552,152		$	536,686