Contingencies (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) name	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 1993
Loss Contingencies [Line Items]
Proceeds from Insurance Settlement, Investing Activities	$ 0	$ 120	$ 0
Loss Contingency, Damages Sought, Value	$ 1,200
Site Contingency, Names of Other Potentially Responsible Parties | name	100
Litigation Settlement, Expense	$ 115
Loss Contingency, Range of Possible Loss, Maximum	1,700
Loss Contingency, Range of Possible Loss, Portion Not Accrued	500
Payments for Environmental Liabilities	6
investment in Trojan				87.00%
Class action damages sought	$ 260