Retirement Plans and Other Postretirement Benefits (Tables)

6 Months Ended

Jun. 30, 2021

Retirement Benefits [Abstract]

Components of Net Periodic Benefit Cost (Income)

: 

	Three Months Ended June 30,
	2021		2020		2021		2020
(Dollars in thousands)	Retirement Plans				Other Post Retirement Benefits
Service cost	$	131	$	116	$	35	$	27
Interest cost	353		417		22		25
Expected loss on plan assets	(901)		(818)		—		—
Amortization of net actuarial loss	317		291		12		6
Net periodic benefit (income) cost	$	(100)	$	6	$	69	$	58

	Six Months Ended June 30,
	2021		2020		2021		2020
(Dollars in thousands)	Retirement Plans				Other Post Retirement Benefits
Service cost	$	261	$	233	$	71	$	55
Interest cost	707		834		43		49
Expected loss on plan assets	(1,793)		(1,634)		—		—
Amortization of net actuarial loss	634		582		24		12
Net periodic benefit (income) cost	$	(191)	$	15	$	138	$	116