Supplemental Guarantor Condensed Consolidating Financial Statements - Condensed Consolidating Statement of Operations (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Sales
Sales	$ 901	$ 1,038
Cost of sales	(774)	(897)
GROSS MARGIN	127	141
Selling, general and administrative	(70)	(34)
Other operating income, net	(5)	0
OPERATING INCOME	52	107
Other income, net	10	11
Equity in earnings of affiliates	6	9
Interest income (expense), net	(14)	(14)
INCOME BEFORE INCOME TAXES	54	113
Benefit (provision) for income taxes	(13)	(21)
Equity income from continuing operations of subsidiaries	0	0
INCOME FROM CONTINUING OPERATIONS	41	92
INCOME FROM DISCONTINUED OPERATIONS, net of tax	0	0
NET INCOME	41	92
Less: Net income attributable to noncontrolling interests	(2)	(2)
Net income	39	90
Eliminations
Sales
Sales	(58)	(89)
Cost of sales	58	89
GROSS MARGIN	0	0
Selling, general and administrative	0	0
Other operating income, net	0
OPERATING INCOME	0	0
Other income, net	0	0
Equity in earnings of affiliates	0	0
Interest income (expense), net	0	0
INCOME BEFORE INCOME TAXES	0	0
Benefit (provision) for income taxes	0	0
Equity income from continuing operations of subsidiaries	(126)	(191)
INCOME FROM CONTINUING OPERATIONS	(126)	(191)
INCOME FROM DISCONTINUED OPERATIONS, net of tax	0	0
NET INCOME	(126)	(191)
Less: Net income attributable to noncontrolling interests	0	0
Net income	(126)	(191)
Parent
Sales
Sales	0	0
Parent | Eliminations
Sales
Sales	0	0
Parent | Reportable Legal Entities
Sales
Sales	0	0
Cost of sales	(16)	(15)
GROSS MARGIN	(16)	(15)
Selling, general and administrative	(24)	(25)
Other operating income, net	0
OPERATING INCOME	(40)	(40)
Other income, net	0	0
Equity in earnings of affiliates	0	0
Interest income (expense), net	(31)	(32)
INCOME BEFORE INCOME TAXES	(71)	(72)
Benefit (provision) for income taxes	12	11
Equity income from continuing operations of subsidiaries	98	151
INCOME FROM CONTINUING OPERATIONS	39	90
INCOME FROM DISCONTINUED OPERATIONS, net of tax	0	0
NET INCOME	39	90
Less: Net income attributable to noncontrolling interests	0	0
Net income	39	90
Guarantors
Sales
Sales	535	589
Guarantors | Eliminations
Sales
Sales	23	32
Guarantors | Reportable Legal Entities
Sales
Sales	558	621
Cost of sales	(469)	(534)
GROSS MARGIN	89	87
Selling, general and administrative	(29)	(27)
Other operating income, net	0
OPERATING INCOME	60	60
Other income, net	7	5
Equity in earnings of affiliates	4	7
Interest income (expense), net	11	12
INCOME BEFORE INCOME TAXES	82	84
Benefit (provision) for income taxes	(15)	(12)
Equity income from continuing operations of subsidiaries	28	40
INCOME FROM CONTINUING OPERATIONS	95	112
INCOME FROM DISCONTINUED OPERATIONS, net of tax	0	0
NET INCOME	95	112
Less: Net income attributable to noncontrolling interests	0	0
Net income	95	112
Non- Guarantors
Sales
Sales	366	449
Non- Guarantors | Eliminations
Sales
Sales	35	57
Non- Guarantors | Reportable Legal Entities
Sales
Sales	401	506
Cost of sales	(347)	(437)
GROSS MARGIN	54	69
Selling, general and administrative	(17)	18
Other operating income, net	(5)
OPERATING INCOME	32	87
Other income, net	3	6
Equity in earnings of affiliates	2	2
Interest income (expense), net	6	6
INCOME BEFORE INCOME TAXES	43	101
Benefit (provision) for income taxes	(10)	(20)
Equity income from continuing operations of subsidiaries	0	0
INCOME FROM CONTINUING OPERATIONS	33	81
INCOME FROM DISCONTINUED OPERATIONS, net of tax	0	0
NET INCOME	33	81
Less: Net income attributable to noncontrolling interests	(2)	(2)
Net income	$ 31	$ 79