Contingencies (Details) $ in Millions	1 Months Ended	3 Months Ended	12 Months Ended
	Nov. 30, 2012 item	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($) a
Environmental remediation
Estimated potential liability for all environmental matters			$ 29
Prior year collections of ICMS amounts realizable		$ 57
Lower Duwamish Site
Environmental remediation
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
Lower Duwamish Site | Minimum
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