Retirement Plans and Other Postretirement Benefits (Tables)

6 Months Ended

Jun. 30, 2018

Retirement Benefits [Abstract]

Components of Net Periodic Benefit Cost (Income)

Components of net periodic benefit cost (income) were as follows:

	Three Months Ended June 30,
	2018			2017			2018		2017
(Dollars in thousands)	Retirement Plans						Other Post Retirement Benefits
Service cost	$	140		$	124		$	22	$	12
Interest cost	439			487			23		30
Expected return on plan assets	(795		)	(748		)	—		—
Amortization of net actuarial loss	281			289			1		10
Accretion of prior service cost	(71		)	(71		)	—		—
Net periodic benefit (income) cost	$	(6	)	$	81		$	46	$	52

	Six Months Ended June 30,
	2018			2017			2018		2017
(Dollars in thousands)	Retirement Plans						Other Post Retirement Benefits
Service cost	$	280		$	275		$	44	$	24
Interest cost	880			952			46		59
Expected return on plan assets	(1,591		)	(1,501		)	—		—
Amortization of net actuarial loss	561			577			2		21
Accretion of prior service cost	(142		)	(141		)	—		—
Net periodic benefit (income) cost	$	(12	)	$	162		$	92	$	104