STATEMENTS OF CONSOLIDATED SHAREHOLDERS' EQUITY (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Statement of Stockholders' Equity [Abstract]
Comprehensive loss, tax	$ (9.6)	$ (7.0)	$ 5.9
Common Stock, Dividends, Per Share, Cash Paid	$ 0.87	$ 0.83	$ 0.78
Stockholders' Equity Attributable to Parent	$ 1,726.1	$ 1,573.3
Accounting Standards Update 2016-06 | Retained Earnings [Member]
Statement of Stockholders' Equity [Abstract]
Reclassification from AOCI, Current Period, Tax	0.2
Stockholders' Equity Attributable to Parent		(5.6)
Reclassification from AOCI, Current Period, Tax	0.2
Accounting Standards Update 2014-09 [Member] | Retained Earnings [Member]
Statement of Stockholders' Equity [Abstract]
Reclassification from AOCI, Current Period, Tax	4.8
Stockholders' Equity Attributable to Parent		$ (4.9)
Reclassification from AOCI, Current Period, Tax	$ 4.8