Employee Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Contributions - Defined benefit plans	$ 18	$ 23	$ 125	$ 93
Contributions - Defined contribution plans	79	82	235	264
United States Pension Plan of US Entity [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions - Defined benefit plans	0
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	96	124	287	373
Interest cost	302	350	908	1,051
Expected return on plan assets	554	566	1,669	1,700
Amortization of prior service credit	(7)	(3)	(22)	(8)
Recognized actuarial net loss (gain)	(135)	(220)	(406)	(662)
Net settlement and curtailment loss	(3)	(128)	(18)	(137)
Total net periodic benefit (income) cost	(25)	253	(72)	515
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	3	3
Interest cost	9	8	25	24
Expected return on plan assets	0	0	0	0
Amortization of prior service credit	0	0	0	0
Recognized actuarial net loss (gain)	1	1	3	3
Net settlement and curtailment loss	0	0	0	0
Total net periodic benefit (income) cost	$ 9	8	25	24
Service cost
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.90%
Interest Cost
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.50%
Change in Assumptions for Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net periodic benefit (income) cost			$ (215)
Discount rate	4.10%
Change in Accounting Estimate, Description			In 2015, we changed the approach we use to estimate the service and interest components of net periodic pension cost for our significant pension plans. Historically, we estimated the service and interest cost components utilizing a single weighted-average discount rate derived from the yield curve used to measure the benefit obligation at the beginning of the period. We elected to utilize a full yield curve approach in the estimation of these components by applying the specific spot rates along the yield curve used in determination of the benefit obligation to the relevant projected cash flows. We made this change to provide a more precise measurement of service and interest costs by improving the correlation between projected benefit cash flows to the corresponding spot yield curve rates. This change does not affect the measurement of our total benefit obligations.
Discontinued Operations [Member]
Defined Benefit Plan Disclosure [Line Items]
Net settlement and curtailment loss	$ 0	110	$ 0	110
Total net periodic benefit (income) cost		$ 25		$ 74