Employment Benefit Plans Change in Plan Assets (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan, Amounts Recognized in Balance Sheet [Abstract]
Pension and Health and Welfare Benefit Plans, Liabilities		$ 151	$ 289
Pension and Health and Welfare Benefit Plans, Current Liabilities		30	30
Pension and Health and Welfare Benefit Plans, Other Assets		200	93
Retiree Health and Welfare Benefits [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of period		0	0
Employer contributions	[1]	19	20
Plan participants' contributions		5	5
Benefits paid		(24)	(25)
Fair value of plan assets at measurement date		0	0
Defined Benefit Plan, Amounts Recognized in Balance Sheet [Abstract]
Funded status (plan assets less projected benefit obligations)		(237)	(258)
Pension Plan [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of period		2,289	2,342
Actual return on plan assets		193	95
Employer contributions	[2]	10	11
Benefits paid		(143)	(145)
Administrative expenses		0	(1)
Settlements		(16)	(13)
Fair value of plan assets at measurement date		2,333	2,289
Defined Benefit Plan, Amounts Recognized in Balance Sheet [Abstract]
Funded status (plan assets less projected benefit obligations)		$ 86	$ (31)

[1] Employer contributions were classified as Other, Net under Operating Activities in the Company’s Consolidated Statements of Cash Flows.

[2] Employer contributions were classified as Other, Net under Operating Activities in the Company’s Consolidated Statements of Cash Flows.