Consolidated Statements of Comprehensive Income - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Net Income (Loss) Attributable to Parent [Abstract]
Sales	$ 2,390	$ 2,285	$ 2,084
Cost of sales	1,580	1,479	1,308
Gross profit	810	806	776
Selling, general and administrative expenses	449	430	396
Net legacy and separation-related expenses	3	14	11
Equity and other income, net	(40)	(33)	(25)
Operating income	398	395	394
Net pension and other postretirement plan expense (income)	60	0	(138)
Net interest and other financing expenses	73	63	42
Income before income taxes	265	332	490
Income tax expense	57	166	186
Net income	$ 208	$ 166	$ 304
NET INCOME PER SHARE
Net income per share, basic (usd per share)	$ 1.10	$ 0.84	$ 1.49
Net income per share, diluted (usd per share)	$ 1.10	$ 0.84	$ 1.49
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING
Weighted average common shares outstanding, basic (in shares)	189	197	204
Weighted average common shares outstanding, diluted (in shares)	189	197	204
Dividends paid per common share (usd per share)	$ 0.424	$ 0.298	$ 0.196
COMPREHENSIVE INCOME
Net income	$ 208	$ 166	$ 304
Other comprehensive (loss) income, net of tax
Currency translation adjustments	(12)	(10)	7
Amortization of pension and other postretirement plan prior service credit	(9)	(9)	(8)
Other comprehensive loss	(21)	(19)	(1)
Comprehensive income	$ 187	$ 147	$ 303