Property, plant and equipment (Tables)

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Major Classes of Property, Plant and Equipment at Cost

The major classes of property, plant and equipment, at cost, at December 31, 2017 and 2016 are as follows:

	2017			2016
	(Dollars in thousands)
Land, buildings and leasehold improvements	$	207,927		$	188,679
Machinery and equipment	384,710			319,471
Computer equipment and software	122,890			108,547
Construction in progress	73,920			47,428
	789,447			664,125
Less: Accumulated depreciation	(406,448		)	(361,226		)
Property, plant and equipment, net	$	382,999		$	302,899