Contingencies (Details) $ in Millions	1 Months Ended	6 Months Ended	12 Months Ended
	Nov. 30, 2012 item	Jun. 30, 2020 USD ($) a	Dec. 31, 2019 USD ($)
Environmental remediation
Number of potentially responsible parties (PRPs) | item	50
Number of industrial companies and governmental entities under review | item	30
Number of PRP groups discussing allocation proposals | item	2
Total site remediation costs expected to cover river bottom area in excess of amount spent to date		$ 342
Area of river bottom to be remediated (in acres) | a		200
Project costs to date		$ 100
Prior year collections of ICMS amounts realizable			$ 57
Other Current Liabilities And Other Noncurrent Liabilities
Environmental remediation
Estimated potential liability for all environmental matters		$ 28