Retirement Plans (Tables)

3 Months Ended

Mar. 31, 2020

Defined Benefit Plan [Abstract]

Net period benefit cost for the pension and postretirement plans

The components of net periodic pension cost and net periodic benefit cost for the RAP and Postretirement Plan for the three months ended March 31, 2020 and 2019 were as follows:

	Three Months Ended March 31,
($ in Thousands)	2020		2019
Components of Net Periodic Benefit Cost
RAP
Service cost	$	2,165	$	1,925
Interest cost	2,008		2,413
Expected return on plan assets	(6,405)		(6,075)
Amortization of prior service cost	(19)		(19)
Amortization of actuarial loss (gain)	808		65
Total net periodic pension cost	$	(1,444)	$	(1,691)
Postretirement Plan
Interest cost	$	20	$	26
Amortization of prior service cost	(19)		(19)
Amortization of actuarial loss (gain)	—		(1)
Total net periodic benefit cost	$	1	$	6