Property, plant and equipment (Tables)

12 Months Ended

Dec. 31, 2018

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, 2018 and 2017 are as follows:

	2018			2017
	(Dollars in thousands)
Land, buildings and leasehold improvements	$	224,605		$	207,927
Machinery and equipment	421,873			384,710
Computer equipment and software	137,899			122,890
Construction in progress	105,319			73,920
	889,696			789,447
Less: Accumulated depreciation	(456,930		)	(406,448		)
Property, plant and equipment, net	$	432,766		$	382,999