Environmental (Schedule of Environmental Remediation Reserves) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Environmental Remediation Obligations [Abstract]
Document Period End Date	Dec. 31, 2020
Demerger obligations (Note 21)	$ 29	$ 23
Divestiture obligations (Note 21)	15	12
Active sites	12	13
US Superfund sites	11	11
Other environmental remediation liabilities	2	2
Total	$ 69	$ 61