Property, Plant and Equipment (Tables)

6 Months Ended

Jun. 30, 2019

Property Plant And Equipment [Abstract]

Schedule of Property, Plant and Equipment

	June 30, 2019			December 31, 2018
(Dollars in thousands)
Land and buildings	$	140,696		$	140,471
Machinery and equipment		791,359			769,451
Leasehold improvements and other		13,435			12,883
Construction in progress		83,930			67,559
		1,029,420			990,364
Accumulated depreciation		(490,727	)		(457,597	)
Property, plant and equipment, net	$	538,693		$	532,767