Revenue Recognition - Cumulative Effect and Impact of New Accounting Pronouncements (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017	Oct. 01, 2018
Statement of Financial Position [Abstract]
Accounts receivable, net	$ 401				$ 409				$ 401	$ 409		$ 376
Inventories, net	194				176				194	176		190
Deferred income taxes	123				138				123	138		144
Accrued expenses and other liabilities	237				203				237	203
Retained deficit	284				399				284	399		412
Statement of Comprehensive Income [Abstract]
Sales	629	$ 613	$ 591	$ 557	594	$ 577	$ 569	$ 545	2,390	2,285	$ 2,084
Cost of sales									1,580	1,479	1,308
Gross profit	217	207	203	183	203	201	207	195	810	806	776
Selling, general and administrative expenses									449	430	396
Equity and other income, net									40	33	25
Operating income	113	102	96	87	105	102	100	88	398	395	394
Income before income taxes									265	332	490
Income tax expense			(2)		2	3	2	71	57	166	186
Net income	$ 27	$ 65	$ 63	$ 53	$ 45	$ 64	$ 67	$ (10)	$ 208	$ 166	$ 304
Earnings per share, basic (usd per share)	$ 0.14	$ 0.34	$ 0.33	$ 0.28	$ 0.23	$ 0.33	$ 0.33	$ (0.05)	$ 1.10	$ 0.84	$ 1.49
Earnings per share, diluted (usd per share)	$ 0.14	$ 0.34	$ 0.33	$ 0.28	$ 0.23	$ 0.33	$ 0.33	$ (0.05)	$ 1.10	$ 0.84	$ 1.49
Under prior guidance
Statement of Financial Position [Abstract]
Accounts receivable, net	$ 438				$ 409				$ 438	$ 409
Inventories, net	179				176				179	176
Deferred income taxes	117				138				117	138
Accrued expenses and other liabilities	236								236
Retained deficit	269				$ 399				269	$ 399
Statement of Comprehensive Income [Abstract]
Sales									2,340
Cost of sales									1,521
Gross profit									819
Selling, general and administrative expenses									456
Equity and other income, net									41
Operating income									401
Income before income taxes									268
Income tax expense									58
Net income									$ 210
Earnings per share, basic (usd per share)									$ 1.11
Earnings per share, diluted (usd per share)									$ 1.11
ASU 2014-09
Statement of Financial Position [Abstract]
Retained deficit												13
ASU 2014-09 | Adjustments
Statement of Financial Position [Abstract]
Accounts receivable, net	37								$ 37			(33)
Inventories, net	(15)								(15)			14
Deferred income taxes	(6)								(6)			6
Accrued expenses and other liabilities	(1)								(1)
Retained deficit	$ (15)								(15)			$ 13
Statement of Comprehensive Income [Abstract]
Sales									(50)
Cost of sales									(59)
Gross profit									9
Selling, general and administrative expenses									7
Equity and other income, net									1
Operating income									3
Income before income taxes									3
Income tax expense									1
Net income									$ 2
Earnings per share, basic (usd per share)									$ 0.01
Earnings per share, diluted (usd per share)									$ 0.01