Commitments and Contingencies Environmental (Details) - Environmental Issue $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($) sites	Mar. 31, 2019 USD ($)
Loss Contingencies [Line Items]
Number of alleged environmental contamination sites | sites	200
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	$ 282	$ 298
Accruals / changes in estimates	1	1
Payments	(5)	(6)
Ending balance	278	293
Current portion of ending balance	40	$ 40
Minimum
Loss Contingencies [Line Items]
Future costs to settle claims and associated liability	225
Maximum
Loss Contingencies [Line Items]
Future costs to settle claims and associated liability	$ 375