Benefit Plans

6 Months Ended

Jun. 30, 2018

Retirement Benefits [Abstract]

Benefit Plans

Note 13 Benefit Plans

Components of net periodic cost included in operating costs and expenses
	Three months ended June 30,						Six months ended June 30,
($ in millions)	2018			2017			2018			2017
Pension benefits
Service cost	$	28		$	28		$	56		$	57
Interest cost	61			66			121			132
Expected return on plan assets	(106		)	(102		)	(211		)	(204		)
Amortization of:
Prior service credit	(14		)	(14		)	(28		)	(28		)
Net actuarial loss	45			47			89			94
Settlement loss	7			8			14			16
Net periodic pension cost	$	21		$	33		$	41		$	67
Postretirement benefits
Service cost	$	2		$	2		$	4		$	4
Interest cost	4			3			7			7
Amortization of:
Prior service credit	(6		)	(6		)	(11		)	(12		)
Net actuarial gain	(5		)	(6		)	(11		)	(12		)
Net periodic postretirement credit	$	(5	)	$	(7	)	$	(11	)	$	(13	)