Employment Benefit Plans (Tables)

9 Months Ended

Sep. 30, 2017

Defined Benefit Plan Disclosure [Line Items]

Schedule of Net Benefit Costs

Components of the net cost for the periods presented below for certain employee benefit plans were as follows (in millions):

	Pension Benefits
	Three Months Ended September 30,
Net Cost (Credit)	2017			2016
Service cost	$	10		$	12
Interest cost	22			23
Expected return on plan assets	(37		)	(35		)
Net credit recognized	$	(5	)	$	—

	Pension Benefits
	Nine Months Ended September 30,
Net Cost (Credit)	2017			2016
Service cost	$	31		$	35
Interest cost	66			71
Expected return on plan assets	(111		)	(107		)
Net credit recognized	$	(14	)	$	(1	)

	Retiree Health and Welfare Benefits
	Three Months Ended September 30,
Net Cost	2017			2016
Interest cost	$	3		$	3
Amortization of prior service credits	(1		)	(1		)
Net cost recognized	$	2		$	2

	Retiree Health and Welfare Benefits
	Nine Months Ended September 30,
Net Cost	2017			2016
Service cost	$	1		$	1
Interest cost	7			8
Amortization of prior service credits	(2		)	(2		)
Net cost recognized	$	6		$	7