CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Net sales	$ 1,889.0	$ 1,796.7	$ 3,465.5	$ 3,491.8
Cost of sales	1,573.9	1,504.3	2,907.8	2,909.9
Gross income	315.1	292.4	557.7	581.9
Operating expenses:
Selling, general and administrative	172.0	157.4	317.4	330.8
Amortization of purchased intangibles	2.3	1.4	3.6	8.4
Total operating expenses	174.3	158.8	321.0	339.2
Operating income	140.8	133.6	236.7	242.7
Other income (expense):
Interest expense	(11.8)	(22.3)	(23.8)	(35.4)
Interest income	0.6	1.6	1.2	2.9
Miscellaneous, net	3.1	(5.8)	1.6	(6.2)
Income before income taxes and earnings (losses) of unconsolidated affiliates	132.7	107.1	215.7	204.0
Provision for income taxes	33.2	38.3	46.4	59.0
Income before earnings (losses) of unconsolidated affiliates	99.5	68.8	169.3	145.0
Equity in earnings (losses) of unconsolidated affiliates	0.1	(0.2)	(0.2)	(0.7)
Net income	$ 99.6	$ 68.6	$ 169.1	$ 144.3
Earnings per share:
Basic	$ 1.45	$ 1.00	$ 2.48	$ 2.12
Diluted	1.44	0.99	2.45	2.09
Cash dividends declared per share on Common Stock	$ 0.33	$ 0.30	$ 0.66	$ 0.60