Condensed Consolidated Statements of Stockholders' Deficit - USD ($) shares in Millions, $ in Millions	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]
Common stock outstanding, at beginning of period (shares) at Sep. 30, 2018		188
Balance at beginning of period at Sep. 30, 2018	$ (358)	$ 2	$ 7	$ (399)	$ 32
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	53			53
Dividends paid	(20)			(20)
Stock-based compensation, net of issuances	1		1
Currency translation adjustments	(4)				(4)
Amortization of pension and other postretirement prior service credits in income, net of tax	(2)				(2)
Common stock outstanding, at end of period (shares) at Dec. 31, 2018		188
Balance at end of period at Dec. 31, 2018	$ (343)	$ 2	8	(379)	26
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends paid per common share (usd per share)	$ 0.106
Common stock outstanding, at beginning of period (shares) at Sep. 30, 2018		188
Balance at beginning of period at Sep. 30, 2018	$ (358)	$ 2	7	(399)	32
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	116
Repurchases of common stock	0
Currency translation adjustments	(2)
Amortization of pension and other postretirement prior service credits in income, net of tax	(4)
Common stock outstanding, at end of period (shares) at Mar. 31, 2019		188
Balance at end of period at Mar. 31, 2019	(298)	$ 2	10	(336)	26
Common stock outstanding, at beginning of period (shares) at Dec. 31, 2018		188
Balance at beginning of period at Dec. 31, 2018	(343)	$ 2	8	(379)	26
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	63			63
Dividends paid	(20)			(20)
Stock-based compensation, net of issuances	2		2	0
Currency translation adjustments	2				2
Amortization of pension and other postretirement prior service credits in income, net of tax	(2)				(2)
Common stock outstanding, at end of period (shares) at Mar. 31, 2019		188
Balance at end of period at Mar. 31, 2019	$ (298)	$ 2	10	(336)	26
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends paid per common share (usd per share)	$ 0.106
Common stock outstanding, at beginning of period (shares) at Sep. 30, 2019	188	188
Balance at beginning of period at Sep. 30, 2019	$ (258)	$ 2	13	(284)	11
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	73			73
Dividends paid	(21)			(21)
Stock-based compensation, net of issuances	3		3
Currency translation adjustments	8				8
Amortization of pension and other postretirement prior service credits in income, net of tax	(2)				(2)
Common stock outstanding, at end of period (shares) at Dec. 31, 2019		188
Balance at end of period at Dec. 31, 2019	$ (196)	$ 2	16	(231)	17
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends paid per common share (usd per share)	$ 0.113
Common stock outstanding, at beginning of period (shares) at Sep. 30, 2019	188	188
Balance at beginning of period at Sep. 30, 2019	$ (258)	$ 2	13	(284)	11
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	136
Repurchases of common stock	(60)
Currency translation adjustments	(13)
Amortization of pension and other postretirement prior service credits in income, net of tax	$ (4)
Common stock outstanding, at end of period (shares) at Mar. 31, 2020	185	185
Balance at end of period at Mar. 31, 2020	$ (237)	$ 2	16	(249)	(6)
Common stock outstanding, at beginning of period (shares) at Dec. 31, 2019		188
Balance at beginning of period at Dec. 31, 2019	(196)	$ 2	16	(231)	17
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	63			63
Dividends paid	(21)			(21)
Repurchases of common stock (in shares)		(3)
Repurchases of common stock	(60)			(60)
Currency translation adjustments	(21)				(21)
Amortization of pension and other postretirement prior service credits in income, net of tax	$ (2)				(2)
Common stock outstanding, at end of period (shares) at Mar. 31, 2020	185	185
Balance at end of period at Mar. 31, 2020	$ (237)	$ 2	$ 16	$ (249)	$ (6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends paid per common share (usd per share)	$ 0.113