Employee Benefits - Schedule of Fair Value of Other Plan Assets (Details) - Other [Member] - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	$ 1,019	$ 1,161	$ 1,061
Cash and cash equivalents [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	11	12
Global [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	270	295
Pooled funds - North America [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	37	42
Pooled funds - Fixed income securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	576	629
Pooled funds - Derivatives [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	12	18
Fixed income securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	30	35
Derivatives [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	48	74
Pooled funds - Commodities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	2	21
Pooled funds - REITS [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	3	3
Alternative investments [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	9	8
Derivatives [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	21	24
Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	11	12
Quoted Prices in Active Markets for Identical Assets (Level 1) | Cash and cash equivalents [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	11	12
Quoted Prices in Active Markets for Identical Assets (Level 1) | Global [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Pooled funds - North America [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Pooled funds - Fixed income securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Pooled funds - Derivatives [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed income securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Derivatives [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Pooled funds - Commodities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Pooled funds - REITS [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Alternative investments [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Derivatives [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	0	0
Significant Other Observable Inputs (Level 2)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	999	1,141
Significant Other Observable Inputs (Level 2) | Cash and cash equivalents [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	0	0
Significant Other Observable Inputs (Level 2) | Global [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	270	295
Significant Other Observable Inputs (Level 2) | Pooled funds - North America [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	37	42
Significant Other Observable Inputs (Level 2) | Pooled funds - Fixed income securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	576	629
Significant Other Observable Inputs (Level 2) | Pooled funds - Derivatives [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	12	18
Significant Other Observable Inputs (Level 2) | Fixed income securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	30	35
Significant Other Observable Inputs (Level 2) | Derivatives [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	48	74
Significant Other Observable Inputs (Level 2) | Pooled funds - Commodities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	2	21
Significant Other Observable Inputs (Level 2) | Pooled funds - REITS [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	3	3
Significant Other Observable Inputs (Level 2) | Alternative investments [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	0	0
Significant Other Observable Inputs (Level 2) | Derivatives [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	21	24
Significant Unobservable Inputs (Level 3)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	9	8	25
Significant Unobservable Inputs (Level 3) | Cash and cash equivalents [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	0	0
Significant Unobservable Inputs (Level 3) | Global [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	0	0
Significant Unobservable Inputs (Level 3) | Pooled funds - North America [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	0	0
Significant Unobservable Inputs (Level 3) | Pooled funds - Fixed income securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	0	0
Significant Unobservable Inputs (Level 3) | Pooled funds - Derivatives [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	0	0
Significant Unobservable Inputs (Level 3) | Fixed income securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	0	0
Significant Unobservable Inputs (Level 3) | Derivatives [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	0	0
Significant Unobservable Inputs (Level 3) | Pooled funds - Commodities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	0	0
Significant Unobservable Inputs (Level 3) | Pooled funds - REITS [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	0	0
Significant Unobservable Inputs (Level 3) | Pooled funds - Real estate [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	0	0	17
Significant Unobservable Inputs (Level 3) | Alternative investments [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	9	8	$ 8
Significant Unobservable Inputs (Level 3) | Derivatives [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total	$ 0	$ 0