Retirement Plans and Other Postretirement Benefits (Tables)

9 Months Ended

Sep. 30, 2017

Retirement Benefits [Abstract]

Components of Net Periodic Benefit Cost (Income)

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

	Three Months Ended September 30,
	2017			2016			2017		2016
(Dollars in thousands)	Retirement Plans						Other Post Retirement Benefits
Service cost	$	124		$	160		$	12	$	11
Interest cost	487			516			29		23
Expected return on plan assets	(797		)	(731		)	—		—
Amortization of net actuarial loss	309			313			11		17
Accretion of prior service cost	(71		)	(71		)	—		—
Net periodic benefit cost	$	52		$	187		$	52	$	51

	Nine Months Ended September 30,
	2017			2016			2017		2016
(Dollars in thousands)	Retirement Plans						Other Post Retirement Benefits
Service cost	$	399		$	501		$	36	$	34
Interest cost	1,439			1,553			88		89
Expected return on plan assets	(2,298		)	(2,238		)	—		—
Amortization of net actuarial loss	886			958			32		30
Accretion of prior service cost	(212		)	(212		)	—		—
Net periodic benefit cost	$	214		$	562		$	156	$	153