Retirement Benefits (Summary of the U.S. and Non-U.S. Plan Investments Measured At Fair Value on a Recurring Basis) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 13,972	$ 14,879
Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,576	3,228
Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	9,722	10,122
Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,674	1,529
Common/Collective trusts
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7,036	7,122
Common/Collective trusts | Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	175	172
Common/Collective trusts | Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6,591	6,766
Common/Collective trusts | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	270	184
Corporate Obligations
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,652	2,941
Corporate Obligations | Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Corporate Obligations | Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,651	2,938
Corporate Obligations | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1	3
Corporate stocks
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,852	2,094
Corporate stocks | Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,844	2,087
Corporate stocks | Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6	6
Corporate stocks | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2	1
Private equity/partnerships
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	710	727
Private equity/partnerships | Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Private equity/partnerships | Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Private equity/partnerships | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	710	727
Government Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	425	371
Government Securities | Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	10	0
Government Securities | Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	415	371
Government Securities | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Real Estate
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	442	381
Real Estate | Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Real Estate | Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	8	6
Real Estate | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	434	375
Short-term investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	316	736
Short-term investment funds | Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	312	724
Short-term investment funds | Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4	12
Short-term investment funds | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Company common stock
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	222	229
Company common stock | Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	222	229
Company common stock | Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Company common stock | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	317	278
Other Investments | Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	13	16
Other Investments | Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	47	23
Other Investments | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 257	$ 239