Property, plant and equipment (Tables)

12 Months Ended

Dec. 31, 2015

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, 2015 and 2014 are as follows:

	2015			2014
	(Dollars in thousands)
Land, buildings and leasehold improvements	$	197,365		$	194,923
Machinery and equipment	313,404			320,999
Computer equipment and software	99,343			107,743
Construction in progress	45,945			51,834
	656,057			675,499
Less: Accumulated depreciation	(339,934		)	(358,064		)
Property, plant and equipment, net	$	316,123		$	317,435