Retirement Plans and Other Postretirement Benefits (Tables)

6 Months Ended

Jun. 30, 2020

Retirement Benefits [Abstract]

Components of Net Periodic Benefit Cost (Income)

Components of net periodic benefit cost were as follows: 

	Three Months Ended June 30,
	2020		2019		2020		2019
(Dollars in thousands)	Retirement Plans				Other Post Retirement Benefits
Service cost	$	116	$	110	$	27	$	16
Interest cost	417		476		25		24
Expected return on plan assets	(818)		(770)		—		—
Amortization of net actuarial loss	291		294		6		—
Accretion of prior service cost	—		(46)		—		—
Net periodic benefit cost	$	6	$	64	$	58	$	40

	Six Months Ended June 30,
	2020		2019		2020		2019
(Dollars in thousands)	Retirement Plans				Other Post Retirement Benefits
Service cost	$	233	$	219	$	55	$	33
Interest cost	834		952		49		47
Expected return on plan assets	(1,634)		(1,541)		—		—
Amortization of net actuarial loss	582		588		12		—
Accretion of prior service cost	—		(91)		—		—
Net periodic benefit cost	$	15	$	127	$	116	$	80