Restructuring Costs - Changes in Restructuring Reserves (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Sep. 30, 2021
Restructuring Reserve [Roll Forward]
Beginning balance	$ 6	$ 10	$ 10
Activity during the period:
Charges	4	6
Cash payments	(4)	(4)
Other	(1)	(2)
Ending balance	5	10	6
Less: non-current restructuring reserves	(1)	0
Restructuring reserves – current	4	10
Employee Termination Benefits
Restructuring Reserve [Roll Forward]
Beginning balance	5	10	10
Activity during the period:
Charges	1	5
Cash payments	(4)	(4)
Other	0	(1)
Ending balance	2	10	5
Less: non-current restructuring reserves	(1)	0
Restructuring reserves – current	1	10
Plant Shutdown & Other
Restructuring Reserve [Roll Forward]
Beginning balance	1	0	0
Activity during the period:
Charges	3	1
Cash payments	0	0
Other	(1)	(1)
Ending balance	3	0	$ 1
Less: non-current restructuring reserves	0	0
Restructuring reserves – current	$ 3	$ 0