Property, Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2016

Property, Plant and Equipment [Abstract]

Schedule of property, plant and equipment

For financial reporting purposes, provisions for depreciation are calculated on a straight‑line basis over the following estimated useful lives of the underlying assets:

	Years
Buildings and improvements	30-40
Machinery and equipment	5-15
Office equipment	3-10

	As of December 31,
(Dollars in thousands)	2016			2015
Land	$	15,855		$	16,726
Buildings and improvements	138,493			141,082
Machinery and equipment	220,238			191,459
Office equipment	54,013			42,696
	428,599			391,963
Accumulated depreciation	(259,178		)	(237,150		)
Property, plant and equipment, net	169,421			154,813
Equipment in process	7,495			23,848
Total property, plant and equipment, net	$	176,916		$	178,661