Employment Benefit Plans Change in Plan Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position [Abstract]
Pension and Health and Welfare Benefit Plans, Current Liabilities	$ 9	$ 3
Pension and Health and Welfare Benefit Plans, Other Assets	465	240
Pension Benefits
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of period	2,336	2,669
Actual return (loss) on plan assets	482	(189)
Employer contributions	0	3
Benefits paid	(134)	(137)
Settlements	(12)	(10)
Fair value of plan assets at measurement date	2,672	2,336
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position [Abstract]
Funded status (plan assets less projected benefit obligations)	$ 377	$ 138