CONDENSED CONSOLIDATED STATEMENTS OF EQUITY - USD ($) shares in Millions, $ in Millions		Total		Common Stock [Member]		Capital in Excess of Par Value [Member]		Retained Earnings [Member]	AOCI Attributable to Parent	Noncontrolling Interests [Member]
Beginning balance at Sep. 30, 2017				254.5
Shares issued under restricted stock plan				0.7
Issuance of common stock, net of stock received for minimum tax withholdings	[1]			1.6
Purchases of common stock		(1.7)		(1.7)
Ending balance at Jun. 30, 2018				255.1
Beginning balance at Sep. 30, 2017				$ 2.5		$ 10,624.9		$ 172.4	$ (457.3)	$ 43.6	[2]
Net income		$ (2.8)								2.6	[2]
Distributions and adjustments to noncontrolling interests	[2]									(27.0)
Net income attributable to common stockholders								1,626.5
Dividends declared (per share - $0.455, $0.43, $1.365 and $1.29)	[3]							(334.0)
Compensation expense under share-based plans						49.2
Issuance of common stock, net of stock received for minimum tax withholdings						33.7	[1]	(6.5)
Other comprehensive income (loss), net of tax		(217.0)	[4]						(217.0)
Purchases of common stock						(70.3)		(30.5)
Ending balance at Jun. 30, 2018		11,412.8		$ 2.5		10,637.5		1,427.9	(674.3)	19.2	[2]
Total Stockholders’ equity at Jun. 30, 2018		11,393.6
Beginning balance at Mar. 31, 2018				256.4
Issuance of common stock, net of stock received for minimum tax withholdings	[1]			0.4
Purchases of common stock				(1.7)
Ending balance at Jun. 30, 2018				255.1
Beginning balance at Mar. 31, 2018				$ 2.6		10,684.6		1,302.4	(441.7)	34.3	[2]
Net income		(3.1)								2.6	[2]
Distributions and adjustments to noncontrolling interests	[2]									(17.7)
Net income attributable to common stockholders								268.2
Dividends declared (per share - $0.455, $0.43, $1.365 and $1.29)	[3]							(112.1)
Compensation expense under share-based plans						15.5
Issuance of common stock, net of stock received for minimum tax withholdings				(0.1)	[1]	7.7	[1]	(0.1)
Other comprehensive income (loss), net of tax									(232.6)
Purchases of common stock						(70.3)		(30.5)
Ending balance at Jun. 30, 2018		11,412.8		$ 2.5		10,637.5		1,427.9	(674.3)	19.2	[2]
Total Stockholders’ equity at Jun. 30, 2018		$ 11,393.6
Beginning balance at Sep. 30, 2018		253.5		253.5
Shares issued under restricted stock plan				3.0
Issuance of common stock, net of stock received for minimum tax withholdings	[1]			2.9
Purchases of common stock		(2.1)		(2.1)
Ending balance at Jun. 30, 2019		257.3		257.3
Beginning balance at Sep. 30, 2018		$ 11,482.4		$ 2.5		10,588.9		1,573.3	(695.3)	13.0	[2]
Net income		(3.4)								2.3	[2]
Contributions	[2]									0.2
Distributions and adjustments to noncontrolling interests	[2]									(1.9)
Adoption of revenue from contracts with customers standard								43.5
Net income attributable to common stockholders								552.1
Dividends declared (per share - $0.455, $0.43, $1.365 and $1.29)	[3]							(361.0)
Compensation expense under share-based plans						52.0
Issuance of common stock, net of stock received for minimum tax withholdings				0.1	[1]	89.9	[1]	(0.4)
Fair value of share-based awards issued in business combinations						70.8
Other comprehensive income (loss), net of tax		(0.1)	[4]						(0.1)
Purchases of common stock						(86.2)		(2.4)
Ending balance at Jun. 30, 2019		11,841.3		$ 2.6		10,715.4		1,805.1	(695.4)	13.6	[2]
Total Stockholders’ equity at Jun. 30, 2019		$ 11,827.7
Beginning balance at Mar. 31, 2019				256.9
Issuance of common stock, net of stock received for minimum tax withholdings	[1]			0.4
Ending balance at Jun. 30, 2019		257.3		257.3
Beginning balance at Mar. 31, 2019				$ 2.6		10,692.5		1,671.2	(725.5)	12.8	[2]
Net income		$ (1.2)								0.9	[2]
Distributions and adjustments to noncontrolling interests	[2]									(0.1)
Net income attributable to common stockholders								252.6
Dividends declared (per share - $0.455, $0.43, $1.365 and $1.29)	[3]							(118.7)
Compensation expense under share-based plans						15.9
Issuance of common stock, net of stock received for minimum tax withholdings	[1]					7.0
Other comprehensive income (loss), net of tax									30.1
Ending balance at Jun. 30, 2019		11,841.3		$ 2.6		$ 10,715.4		$ 1,805.1	$ (695.4)	$ 13.6	[2]
Total Stockholders’ equity at Jun. 30, 2019		$ 11,827.7

[1] Included in the issuance of common stock in the nine months ended June 30, 2019 is the issuance of approximately 1.6 million shares of Common Stock (as hereinafter defined) valued at $70.1 million in connection with the KapStone Acquisition (as hereinafter defined).

[2] Excludes amounts related to contingently redeemable noncontrolling interests, which are separately classified outside of permanent equity on the Condensed Consolidated Balance Sheets.

[3] Includes cash dividends paid, dividend equivalent units on certain restricted stock awards and dividends declared but unpaid related to the shares reserved but unissued at the time of the acquisition of Smurfit-Stone Container Corporation (“Smurfit-Stone”) for the resolution of Smurfit Stone bankruptcy claims.

[4] All amounts are net of tax and noncontrolling interests.