Equity Items - Summary of Reconciliation of Changes in Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		6 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Balance, end of period		$ 2,983	$ 3,362	$ 2,983	$ 3,362
Cash dividends declared per common share		$ 0.275	$ 0.250	$ 0.550	$ 0.500
Common Stock and Paid in Capital [Member]
Balance, beginning of period		$ 758	$ 948	$ 757	$ 947
Common shares issued under stock incentive and other plans	[1]	8	5	9	6
Balance, end of period		766	953	766	953
Retained earnings [Member]
Balance, beginning of period		3,239	2,719	3,224	2,750
Adoption of new accounting pronouncements	[2]		1		34
Net income (loss)		(582)	76	(550)	28
Regular dividends		(16)	(16)	(33)	(32)
Balance, end of period		2,641	2,780	2,641	2,780
Accumulated other comprehensive income (loss) [Member]
Balance, beginning of period		(372)	(362)	(410)	(291)
Adoption of new accounting pronouncements	[2]				(34)
Unrealized translation gain (loss)		(52)	(9)	(14)	(40)
Pension and postretirement obligation adjustment					(6)
Balance, end of period		$ (424)	$ (371)	$ (424)	$ (371)

[1] Common shares issued were 208,564 shares and 93,738 shares for the three months ended March 31, 2020 and 2019, respectively, and 279,025 shares and 234,352 shares for the six months ended March 31, 2020 and 2019.

[2] Represents the cumulative-effect adjustment related to the adoption of the new guidance related to the accounting for equity securities and tax effects of intercompany transfers during fiscal 2019.