Retirement Plans (Tables)

6 Months Ended

Jun. 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 six months ended June 30, 2016 and 2015 were as follows.

	Three Months Ended June 30,						Six Months Ended June 30,
	2016			2015			2016			2015
	($ in Thousands)
Components of Net Periodic Benefit Cost
Pension Plan:
Service cost	$	1,725		$	3,062		$	3,450		$	6,125
Interest cost	1,780			1,643			3,560			3,285
Expected return on plan assets	(5,065		)	(5,350		)	(10,130		)	(10,700		)
Amortization of prior service cost	12			12			25			25
Amortization of actuarial loss	483			533			965			1,065
Total net periodic pension cost	$	(1,065	)	$	(100	)	$	(2,130	)	$	(200	)
Postretirement Plan:
Interest cost	$	36		$	35		$	72		$	70
Total net periodic benefit cost	$	36		$	35		$	72		$	70