Inventories (Tables)

6 Months Ended

Jun. 30, 2018

Inventory Disclosure [Abstract]

Summary of Inventories

	June 30, 2018		December 31, 2017
(Dollars in thousands)
Raw materials	$	49,801	$	59,353
Work in process		54,408		48,803
Finished goods		82,809		65,843
Inventories	$	187,018	$	173,999