Employee Benefits Schedule of Fair Value, Assets (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Money Market Funds, at Carrying Value	$ 21	$ 18
Investments, Fair Value Disclosure	2	2
Equity securities:
Domestic	52	44
Defined Benefit Plan, Fair Value of Plan Assets		550
Financial Instruments, Owned, at Fair Value	23	21
Other Postretirement Benefit Plans assets: [Abstract]
Money market funds		0
Domestic equity securities - Other postretirement benefit plan assets at fair value		3
International equity securities - other post retirement assets at fair value		8
Private Equity Funds, Domestic [Member]
Defined Benefit Plan Disclosure [Line Items]
Money Market Funds, at Carrying Value	6	5
Investments, Fair Value Disclosure	18	22
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments, Fair Value Disclosure	483	479
Fair Value, Inputs, Level 1 [Member]
Equity securities:
Domestic	52	44
Private equity funds	0	0
Defined Benefit Plan, Fair Value of Plan Assets	52	44
Financial Instruments, Owned, at Fair Value	8	10
Other Postretirement Benefit Plans assets: [Abstract]
Money market funds	4	0
Domestic equity securities - Other postretirement benefit plan assets at fair value	0	0
International equity securities - other post retirement assets at fair value	8	8
Other post retirement benefit plan assets total	12	8
Fair Value, Inputs, Level 2 [Member]
Equity securities:
Domestic	0	0
Private equity funds	0	0
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Financial Instruments, Owned, at Fair Value	39	26
Other Postretirement Benefit Plans assets: [Abstract]
Money market funds	0	0
Domestic equity securities - Other postretirement benefit plan assets at fair value	3	3
International equity securities - other post retirement assets at fair value	0	0
Other post retirement benefit plan assets total	7	8
Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Money Market Funds, at Carrying Value	0
Equity securities:
Domestic	0	0
Private equity funds	0	0
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Financial Instruments, Owned, at Fair Value	2	0
Other Postretirement Benefit Plans assets: [Abstract]
Money market funds	0	0
Domestic equity securities - Other postretirement benefit plan assets at fair value	0	0
International equity securities - other post retirement assets at fair value	0	0
Other post retirement benefit plan assets total	0	0
Pension Plan [Member]
Equity securities:
Defined Benefit Plan, Fair Value of Plan Assets	559	550	$ 591
Financial Instruments, Owned, at Fair Value	507	506
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Money Market Funds, at Carrying Value	4	7
Investments, Fair Value Disclosure	7	7
Equity securities:
Defined Benefit Plan, Fair Value of Plan Assets	30	30	$ 32
Financial Instruments, Owned, at Fair Value	11	$ 14
Other Postretirement Benefit Plans assets: [Abstract]
Money market funds	4
Domestic equity securities - Other postretirement benefit plan assets at fair value	3
International equity securities - other post retirement assets at fair value	$ 8