Defined Benefit Postretirement Plans (Details) - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Dec. 31, 2015	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Pension and Other Postretirement Benefit Contributions [Abstract]
Pension Contributions					$ 65
Defined Benefit Plan, Benefits Paid					57
Other Postretirement Benefits Payments					13
Scenario, Forecast [Member]
Pension and Other Postretirement Benefit Contributions [Abstract]
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year		$ 18
United States and Foreign Pension Plans Defined Benefit [Member]
Defined Benefit Plan Net Periodic Benefit Cost [Line Items]
Service cost			$ 11	$ 12	35	$ 35
Interest cost			12	15	39	46
Expected return on plan assets			(17)	(16)	(53)	(48)
Amortization:
- prior service cost (credit)			(3)	1	(4)	4
-actuarial loss (gain)			5	7	19	23
Net settlement loss	[1]		18	22	99	93
Defined Benefit Plan, Curtailments	[2]		4	0	5	0
Net periodic benefit cost			30	41	140	153
Other Postretirement Benefit Plans Defined Benefit [Member]
Defined Benefit Plan Net Periodic Benefit Cost [Line Items]
Service cost			0	0	2	2
Interest cost			3	4	8	10
Expected return on plan assets			0	0	0	0
Amortization:
- prior service cost (credit)			(1)	(1)	(3)	(3)
-actuarial loss (gain)			1	0	1	0
Net settlement loss	[1]		0	0	0	0
Defined Benefit Plan, Curtailments	[2]		0	0	(4)	0
Net periodic benefit cost			$ 3	$ 3	$ 4	$ 9

[1] Settlements are recognized as they occur, once it is probable that lump sum payments from a plan for a given year will exceed the plan's total service and interest cost for that year.

[2] Related to workforce reductions, which reduced the future expected years of service for employees participating in the plans and the impact of discontinuing accruals for future benefits under the U.K. pension plan effective December 31, 2015.