Pension Benefits Fair Value of Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	$ 1,212	$ 1,209
Cash
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	61	31
Time Deposits
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	10	9
Equity Funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	423	457
Bond Mutual Funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	469	230
Real Estate Trust Funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	29	39
Hedge Funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	107	102
Insurance Contracts
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	5	1
Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	51	286
Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	57	54
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	169	367
Level 1 | Cash
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	61	31
Level 1 | Time Deposits
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Level 1 | Equity Funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Level 1 | Bond Mutual Funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Level 1 | Real Estate Trust Funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Level 1 | Hedge Funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Level 1 | Insurance Contracts
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Level 1 | Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	51	282
Level 1 | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	57	54
Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	902	700
Level 2 | Cash
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Level 2 | Time Deposits
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	10	9
Level 2 | Equity Funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	423	457
Level 2 | Bond Mutual Funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	469	230
Level 2 | Real Estate Trust Funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Level 2 | Hedge Funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Level 2 | Insurance Contracts
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Level 2 | Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	4
Level 2 | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	141	142
Level 3 | Cash
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Level 3 | Time Deposits
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Level 3 | Equity Funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Level 3 | Bond Mutual Funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Level 3 | Real Estate Trust Funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	29	39	$ 41
Level 3 | Hedge Funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	107	102	102
Level 3 | Insurance Contracts
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	5	1	$ 1
Level 3 | Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Level 3 | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	$ 0	$ 0