Retirement Plans (Tables)

3 Months Ended

Mar. 31, 2018

Retirement Plans [Abstract]

Net Periodic Benefit Cost

	Pension Benefits
	For the three months ended
	March 31,
($ in millions)	2018		2017
Components of total pension benefit cost
Service cost	$	24	$	25
Interest cost on projected benefit obligation		30		34
Expected return on plan assets		(50)		(48)
Amortization of unrecognized loss		7		8
Net periodic pension benefit cost	$	11	$	19
Pension settlement costs		-		43
Total pension benefit cost	$	11	$	62
	Postretirement Benefits
	For the three months ended
	March 31,
($ in millions)	2018		2017
Components of net periodic postretirement benefit cost
Service cost	$	5	$	5
Interest cost on projected benefit obligation		9		10
Amortization of prior service cost/(credit)		(2)		(2)
Amortization of unrecognized (gain) loss		1		-
Net periodic postretirement benefit cost	$	13	$	13