Employee Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plans	$ 75	$ 45
Defined Contribution Plans	$ 78	96
Defined Benefit Plan, Discount Rate Used to Measure Service Cost	3.90%
Defined Benefit Plan, Discount Rate Used to Measure Interest Costs	3.50%
Defined Benefit Plan, Discount Rate, Previous Method	4.10%
Change in net periodic benefit cost due to change in accounting estimate	$ (215)
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost	94	125
Interest Cost	302	351
Expected Return on Plan Assets	556	569
Amortization	(8)	(3)
Recognized actuarial net loss (gain)	(135)	(221)
Net settlement and curtailment loss	(12)	(6)
Net periodic benefit (income) cost	(21)	131
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost	1	1
Interest Cost	8	8
Expected Return on Plan Assets	0	0
Amortization	0	0
Recognized actuarial net loss (gain)	1	1
Net settlement and curtailment loss	0	0
Net periodic benefit (income) cost	$ 8	$ 8