CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Revenues	$ 2,175.8	$ 2,036.9	$ 5,648.5	$ 4,866.6
Cost of sales	1,772.9	1,650.0	4,668.0	4,018.7
Gross income	402.9	386.9	980.5	847.9
Operating expenses:
Selling, general and administrative	171.2	163.9	499.3	484.7
Amortization of purchased intangibles	9.3	11.1	29.1	34.7
Total operating expenses	180.5	175.0	528.4	519.4
Operating income	222.4	211.9	452.1	328.5
Other income (expense):
Interest expense	(25.4)	(15.3)	(56.9)	(45.1)
Interest income	1.9	1.4	11.7	3.2
Miscellaneous, net	(1.8)	0.6	(2.1)	3.1
Income before income taxes and earnings of unconsolidated affiliates	197.1	198.6	404.8	289.7
Provision for income taxes	44.6	70.1	85.5	98.9
Income before earnings of unconsolidated affiliates	152.5	128.5	319.3	190.8
Equity in earnings of unconsolidated affiliates	0.9	0.1	1.3	1.3
Net income	$ 153.4	$ 128.6	$ 320.6	$ 192.1
Earnings per share:
Basic earnings per share (in dollars per share)	$ 2.08	$ 1.72	$ 4.31	$ 2.57
Diluted earnings per share (in dollars per share)	2.05	1.69	4.25	2.54
Cash dividends declared per share on common stock (in dollars per share)	$ 0.24	$ 0.21	$ 0.72	$ 0.63