Retirement Plans (Tables)

6 Months Ended

Jun. 30, 2019

Retirement Plans [Abstract]

Net Periodic Benefit Cost

	Pension Benefits
	For the three months ended				For the six months ended
	June 30,				June 30,
($ in millions)	2019		2018		2019		2018
Components of total pension benefit cost
Service cost	$	21	$	24	$	42	$	48
Interest cost on projected benefit obligation		32		30		65		60
Expected return on plan assets		(43)		(48)		(86)		(98)
Amortization of unrecognized loss		14		6		28		13
Net periodic pension benefit cost	$	24	$	12	$	49	$	23
Pension settlement costs		-		25		-		25
Total pension benefit cost	$	24	$	37	$	49	$	48
	Postretirement Benefits
	For the three months ended				For the six months ended
	June 30,				June 30,
($ in millions)	2019		2018		2019		2018
Components of net periodic postretirement benefit cost
Service cost	$	5	$	6	$	10	$	11
Interest cost on projected benefit obligation		11		10		21		19
Amortization of prior service cost (credit)		(3)		(3)		(4)		(5)
Amortization of unrecognized (gain) loss		-		-		(2)		1
Net periodic postretirement benefit cost	$	13	$	13	$	25	$	26