Retirement Plans (Tables)

9 Months Ended

Sep. 30, 2016

Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]

Net period benefit cost for the pension and postretirement plans

The components of net periodic benefit cost for the RAP and Postretirement Plans for three and nine months ended September 30, 2016 and 2015 were as follows.

	Three Months Ended September 30,						Nine Months Ended September 30,
	2016			2015			2016			2015
	($ in Thousands)
Components of Net Periodic Benefit Cost
Pension Plan:
Service cost	$	1,636		$	2,318		$	5,086		$	8,443
Interest cost	1,781			1,678			5,341			4,963
Expected return on plan assets	(5,085		)	(5,379		)	(15,215		)	(16,079		)
Amortization of prior service cost	(80		)	12			(55		)	37
Amortization of actuarial loss	621			627			1,586			1,692
Total net periodic pension cost	$	(1,127	)	$	(744	)	$	(3,257	)	$	(944	)
Postretirement Plan:
Interest cost	$	35		$	35		$	107		$	105
Total net periodic benefit cost	$	35		$	35		$	107		$	105