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, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Investments measured at NAV	$ 7,939	$ 8,013
Total investments	14,332	13,972
Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total investments	2,618	2,576
Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total investments	3,452	3,123
Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total investments	323	260
Common/Collective trusts
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6,821	7,036
Investments measured at NAV	6,805	6,861
Common/Collective trusts | Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	16	175
Common/Collective trusts | Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Common/Collective trusts | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Corporate Obligations
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,033	2,652
Investments measured at NAV	0	0
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	3,024	2,651
Corporate Obligations | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	9	1
Corporate stocks
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,014	1,852
Investments measured at NAV	0	0
Corporate stocks | Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,009	1,844
Corporate stocks | Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3	6
Corporate stocks | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2	2
Private equity/partnerships
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	722	710
Investments measured at NAV	722	710
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	0	0
Government Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	391	425
Investments measured at NAV	0	0
Government Securities | Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11	10
Government Securities | Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	380	415
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	412	442
Investments measured at NAV	412	442
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	0	0
Real Estate | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Short-term investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	319	316
Investments measured at NAV	0	0
Short-term investment funds | Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	297	312
Short-term investment funds | Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	22	4
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	270	222
Investments measured at NAV	0	0
Company common stock | Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	270	222
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	350	317
Investments measured at NAV	0	0
Other Investments | Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	15	13
Other Investments | Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	23	47
Other Investments | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 312	$ 257