STATEMENTS OF CONSOLIDATED SHAREHOLDERS' EQUITY (Parenthetical) - USD ($)	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Statement of Stockholders' Equity [Abstract]
Comprehensive loss, tax	$ 10,700,000	$ (9,600,000)	$ (7,000,000.0)
Common Stock, Dividends, Per Share, Cash Paid	$ 0.94	$ 0.87	$ 0.83
Reclassification from AOCI, Current Period, Tax			$ 0.2
Stockholders' Equity Attributable to Parent	$ 1,879.7	$ 1,726,100,000	4.9
Reclassification from AOCI, Current Period, Tax			0.2
Other Comprehensive Income (Loss), Tax	$ (10,700,000)	$ 9,600,000	$ 7,000,000.0
Common Stock, Dividends, Per Share, Cash Paid	$ 0.94	$ 0.87	$ 0.83
Stockholders' Equity Attributable to Parent	$ 1,879.7	$ 1,726,100,000	$ 4.9
Accounting Standards Update 2016-06 | Retained Earnings [Member]
Statement of Stockholders' Equity [Abstract]
Stockholders' Equity Attributable to Parent			(5,600,000)
Stockholders' Equity Attributable to Parent			(5,600,000)
Accounting Standards Update 2014-09 [Member] | Retained Earnings [Member]
Statement of Stockholders' Equity [Abstract]
Reclassification from AOCI, Current Period, Tax			4,800,000
Stockholders' Equity Attributable to Parent			(4,900,000)
Reclassification from AOCI, Current Period, Tax			4,800,000
Stockholders' Equity Attributable to Parent			$ (4,900,000)
Accounting Standards Update 2016-13 | Retained Earnings [Member]
Statement of Stockholders' Equity [Abstract]
Reclassification from AOCI, Current Period, Tax	800,000
Stockholders' Equity Attributable to Parent	(2,200,000)
Reclassification from AOCI, Current Period, Tax	800,000
Stockholders' Equity Attributable to Parent	$ (2,200,000)