Inventories (Tables)

3 Months Ended

Mar. 31, 2018

Inventories [Abstract]

Inventories

	March 31,		December 31,
	2018		2017
	(Dollars in thousands)
Raw materials	$	121,840	$	112,300
Work in process		54,626		39,454
Finished goods		181,617		172,426
Total inventories	$	358,083	$	324,180