Retirement Plans (Tables)

3 Months Ended

Mar. 31, 2017

Retirement Plans [Abstract]

Net Periodic Benefit Cost

	Pension Benefits
	For the three months ended
	March 31,
($ in millions)	2017		2016
Components of total pension benefit cost
Service cost	$	25	$	13
Interest cost on projected benefit obligation		34		23
Expected return on plan assets		(48)		(28)
Amortization of unrecognized loss		8		11
Net periodic pension benefit cost		19		19
Pension settlement costs		43		-
Total pension benefit cost	$	62	$	19

	Postretirement Benefits
	Other Than Pensions (OPEB)
	For the three months ended
	March 31,
($ in millions)	2017		2016
Components of net periodic postretirement benefit cost
Service cost	$	5	$	3
Interest cost on projected benefit obligation		10		7
Amortization of prior service cost/(credit)		(2)		(2)
Amortization of unrecognized loss		-		-
Net periodic postretirement benefit cost	$	13	$	8