Property, Plant and Equipment (Tables)

3 Months Ended

Mar. 31, 2019

Property Plant And Equipment [Abstract]

Schedule of Property, Plant and Equipment

	March 31, 2019			December 31, 2018
(Dollars in thousands)
Land and buildings	$	137,655		$	140,471
Machinery and equipment		774,058			769,451
Leasehold improvements and others		12,730			12,883
Construction in progress		74,550			67,559
		998,993			990,364
Accumulated depreciation		(471,969	)		(457,597	)
Property, plant and equipment, net	$	527,024		$	532,767