Restructuring, Impairment and Plant Closing and Transition Costs - Cash and Noncash Restructuring Charges (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Restructuring and Related Activities [Abstract]
Cash charges									$ 25	$ 37	$ 45
Pension-related charges										25
Early Settlement of contractual obligations									(14)
Accelerated depreciation									22	556	3
Impairment of assets											3
Other non-cash charges										10	1
Total restructuring, impairment and plant closing and Transition costs	$ 9	$ 12	$ 0	$ 12	$ 55	$ 428	$ 136	$ 9	$ 33	$ 628	$ 52