Employee Benefit Plans (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Pension Contributions			$ 2,008,000,000	$ 125,000,000
Contributions - Defined benefit plans	$ 1,929,000,000	$ 18,000,000	2,008,000,000	125,000,000
Contributions - Defined contribution plans	86,000,000	79,000,000	262,000,000	235,000,000
Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Contributions	1,900,000,000	0	1,900,000,000	0
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	94,000,000	96,000,000	280,000,000	287,000,000
Interest cost	281,000,000	302,000,000	838,000,000	908,000,000
Expected return on plan assets	555,000,000	554,000,000	1,636,000,000	1,669,000,000
Amortization of prior service credit	(9,000,000)	(7,000,000)	(27,000,000)	(22,000,000)
Recognized actuarial net loss (gain)	(144,000,000)	(135,000,000)	(430,000,000)	(406,000,000)
Net settlement and curtailment (gain) loss	(2,000,000)	(3,000,000)	(1,000,000)	(18,000,000)
Total net periodic benefit (income) cost	(43,000,000)	(25,000,000)	(114,000,000)	(72,000,000)
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	0	1,000,000	2,000,000	3,000,000
Interest cost	9,000,000	9,000,000	22,000,000	25,000,000
Expected return on plan assets	0	0	0	0
Amortization of prior service credit	(1,000,000)	0	(1,000,000)	0
Recognized actuarial net loss (gain)	2,000,000	1,000,000	7,000,000	3,000,000
Net settlement and curtailment (gain) loss	0	0	0	0
Total net periodic benefit (income) cost	$ 6,000,000	$ 9,000,000	$ 16,000,000	$ 25,000,000