Retirement Benefits (Tables)

3 Months Ended

Mar. 31, 2018

Retirement Benefits [Abstract]

Net Periodic Benefit (Credit) Cost

	U.S. Pension Plans				Non-U.S. Pension Plans				Other Benefit Plans
	Three Months Ended March 31,
	2018		2017		2018		2017		2018		2017
	(Dollars in thousands)
Service cost	$	3	$	4	$	461	$	404	$	1	$	—
Interest cost		2,788		3,666		689		573		183		211
Expected return on plan assets		(3,995)		(4,740)		(233)		(210)		—		—
Amortization of prior service cost		—		2		11		10		—		—
Net periodic benefit (credit) cost	$	(1,204)	$	(1,068)	$	928	$	777	$	184	$	211