Employee Benefit Plans (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Pension Contributions			$ 79,000,000	$ 107,000,000
Contributions - Defined benefit plans	$ 33,000,000	$ 32,000,000	79,000,000	107,000,000
Contributions - Defined contribution plans	86,000,000	78,000,000	176,000,000	156,000,000
Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Contributions	0	0	0	0
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	93,000,000	97,000,000	186,000,000	191,000,000
Interest cost	279,000,000	304,000,000	557,000,000	606,000,000
Expected return on plan assets	541,000,000	559,000,000	1,081,000,000	1,115,000,000
Amortization of prior service credit	(9,000,000)	(7,000,000)	(18,000,000)	(15,000,000)
Recognized actuarial net loss (gain)	(143,000,000)	(136,000,000)	(286,000,000)	(271,000,000)
Net settlement and curtailment (gain) loss	2,000,000	(3,000,000)	1,000,000	(15,000,000)
Total net periodic benefit (income) cost	(37,000,000)	(26,000,000)	(71,000,000)	(47,000,000)
Defined Benefit Plan, Accumulated Benefit Obligation, Increase (Decrease) for Plan Amendment			(170,000,000)
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1,000,000	1,000,000	2,000,000	2,000,000
Interest cost	6,000,000	8,000,000	13,000,000	16,000,000
Expected return on plan assets	0	0	0	0
Amortization of prior service credit	0	0	0	0
Recognized actuarial net loss (gain)	2,000,000	1,000,000	5,000,000	2,000,000
Net settlement and curtailment (gain) loss	0	0	0	0
Total net periodic benefit (income) cost	$ 5,000,000	$ 8,000,000	$ 10,000,000	$ 16,000,000