Condensed Consolidating Information - Consolidating cash flow statement (Details) - USD ($) $ in Millions	9 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Condensed Cash Flow Statements
Net cash provided by (used in) operating activities	$ 156.3	$ 103.7
Investing activities:
Capital expenditures	(16.3)	(14.2)
Proceeds from sales of property, plant, and equipment	0.4	2.3
Other, net	0.2	(0.4)
Net cash used in investing activities	(15.7)	(12.3)
Financing activities:
Repayments on term loan	(148.5)	(10.1)
Proceeds from revolving credit facilities, net of financing costs	946.5	721.2
Repayments on revolving credit facilities	(837.2)	(725.5)
Payment of dividends on common stock	(39.1)	(39.0)
Repurchases of common stock	(60.6)	(28.0)
Net proceeds on stock plans	6.2	11.4
Other, net	(1.8)	(2.5)
Net cash used in financing activities	(134.5)	(72.5)
Effect of exchange rates on cash and cash equivalents	(1.0)	0.6
Net cash flows	5.1	19.5
At beginning of period	66.0	52.0
At end of period	71.1	71.5
Reportable legal entities | Parent
Condensed Cash Flow Statements
Net cash provided by (used in) operating activities	186.0	33.2
Investing activities:
Capital expenditures	(1.5)	(0.5)
Proceeds from sales of property, plant, and equipment		0.0
Other, net	0.0	2.7
Net cash used in investing activities	(1.5)	2.2
Financing activities:
Repayments on term loan	(148.5)	(10.1)
Proceeds from revolving credit facilities, net of financing costs	530.6	233.0
Repayments on revolving credit facilities	(472.9)	(207.0)
Payment of dividends on common stock	(39.1)	(39.0)
Repurchases of common stock	(60.6)	(28.0)
Net proceeds on stock plans	6.2	11.4
Other, net	0.0	0.0
Net cash used in financing activities	(184.3)	(39.7)
Net cash flows	0.2	(4.3)
At beginning of period	0.1	4.4
At end of period	0.3	0.1
Reportable legal entities | Guarantors
Condensed Cash Flow Statements
Net cash provided by (used in) operating activities	126.6	129.0
Investing activities:
Capital expenditures	(7.5)	(7.2)
Proceeds from sales of property, plant, and equipment	0.0	1.9
Other, net	0.1	(0.4)
Net cash used in investing activities	(7.4)	(5.7)
Financing activities:
Payment of Intercompany Dividends	(118.3)	(122.6)
Net cash used in financing activities	(118.3)	(122.6)
Net cash flows	0.9	0.7
At beginning of period	4.9	5.6
At end of period	5.8	6.3
Reportable legal entities | Non-Guarantors
Condensed Cash Flow Statements
Net cash provided by (used in) operating activities	(32.0)	70.2
Investing activities:
Capital expenditures	(7.3)	(6.5)
Proceeds from sales of property, plant, and equipment	0.4	0.4
Other, net	0.1	(2.7)
Net cash used in investing activities	(6.8)	(8.8)
Financing activities:
Proceeds from revolving credit facilities, net of financing costs	415.9	488.2
Repayments on revolving credit facilities	(364.3)	(518.5)
Payment of Intercompany Dividends	(6.0)	(6.1)
Other, net	(1.8)	(2.5)
Net cash used in financing activities	43.8	(38.9)
Effect of exchange rates on cash and cash equivalents	(1.0)	0.6
Net cash flows	4.0	23.1
At beginning of period	61.0	42.0
At end of period	65.0	65.1
Eliminations
Condensed Cash Flow Statements
Net cash provided by (used in) operating activities	(124.3)	(128.7)
Financing activities:
Payment of Intercompany Dividends	124.3	128.7
Net cash used in financing activities	$ 124.3	$ 128.7