Other Comprehensive Income (Schedule of Changes in AOCL by Component) (Details) - USD ($)	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]
Prior to reclassification	$ (66,900,000)	$ 4,900,000	$ 67,700,000
Reclassification from	(4,200,000)	(2,000,000.0)	6,000,000.0
Pre-tax	(71,100,000)	2,900,000	73,700,000
Tax effect	(7,000,000.0)	5,900,000	14,600,000
Other comprehensive income (loss)	(64,100,000)	(3,000,000.0)	59,100,000
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	1,616,200,000
Other comprehensive income (loss)	(64,100,000)	(3,000,000.0)	59,100,000
Ending balance3	1,573,300,000	1,616,200,000
Derivative Instruments and Hedges [Member]
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]
Prior to reclassification	(7,400,000)	21,000,000.0	12,700,000
Reclassification from	6,200,000	5,000,000.0	(900,000)
Pre-tax	(13,600,000)	16,000,000.0	11,800,000
Tax effect	3,200,000	(3,500,000)	4,400,000
Other comprehensive income (loss)	(10,400,000)	12,500,000	7,400,000
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	16,800,000	4,300,000	(3,100,000)
Other comprehensive income (loss)	(10,400,000)	12,500,000	7,400,000
Ending balance3	7,200,000	16,800,000	4,300,000
Derivative Instruments and Hedges [Member] | Foreign Exchange Forward [Member]
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]
Prior to reclassification	(600,000)	400,000	(400,000)
Reclassification from	600,000	(300,000)	(200,000)
Pre-tax	0	700,000	(600,000)
Tax effect	0	(100,000)	(100,000)
Other comprehensive income (loss)	0	600,000	(500,000)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	200,000	(400,000)	100,000
Other comprehensive income (loss)	0	600,000	(500,000)
Ending balance3	200,000	200,000	(400,000)
Derivative Instruments and Hedges [Member] | Currency Swap [Member]
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]
Prior to reclassification	18,000,000.0
Reclassification from	0
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(1,700,000)
Ending balance3	12,200,000	(1,700,000)
Derivative Instruments and Hedges [Member] | Interest Rate Swap [Member]
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]
Prior to reclassification	(24,800,000)	22,800,000
Reclassification from	(6,800,000)	5,300,000	(700,000)
Pre-tax	(31,600,000)	17,500,000	12,400,000
Tax effect	(7,300,000)	(3,900,000)	(4,500,000)
Other comprehensive income (loss)	(24,300,000)	13,600,000	7,900,000
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	18,300,000	4,700,000	(3,200,000)
Other comprehensive income (loss)	(24,300,000)	13,600,000	7,900,000
Ending balance3	(5,200,000)	18,300,000	4,700,000
Derivative Instruments and Hedges [Member] | Cross Currency Interest Rate Contract [Member]
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]
Prior to reclassification		(2,200,000)
Reclassification from		0
Pre-tax		(2,200,000)
Tax effect		500,000
Other comprehensive income (loss)		(1,700,000)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(1,700,000)	0
Other comprehensive income (loss)		(1,700,000)
Ending balance3		(1,700,000)	0
Derivative Instruments and Hedges [Member] | Foreign Exchange Contract [Member]
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]
Pre-tax	18,000,000.0
Tax effect	4,100,000
Other comprehensive income (loss)	13,900,000
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income (loss)	13,900,000
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]
Prior to reclassification	(40,100,000)	(24,000,000.0)	32,900,000
Reclassification from	0	0	(1,000,000.0)
Pre-tax	(40,100,000)	(24,000,000.0)	33,900,000
Tax effect	0	0	0
Other comprehensive income (loss)	(40,100,000)	(24,000,000.0)	33,900,000
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(105,300,000)	(81,300,000)	(115,200,000)
Other comprehensive income (loss)	(40,100,000)	(24,000,000.0)	33,900,000
Ending balance3	(145,400,000)	(105,300,000)	(81,300,000)
Accumulated Foreign Currency Adjustment Attributable to Parent [Member] | Interest Rate Swap [Member]
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]
Prior to reclassification			13,100,000
Change in Pension and Postretiremen Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	6,200,000
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]
Prior to reclassification	(19,400,000)	7,900,000	22,100,000
Reclassification from	(2,000,000.0)	3,000,000.0	(5,900,000)
Pre-tax	(17,400,000)	10,900,000	28,000,000.0
Tax effect	3,800,000	2,400,000	(10,200,000)
Other comprehensive income (loss)	(13,600,000)	8,500,000	17,800,000
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(24,500,000)	(33,000,000.0)	(50,800,000)
Other comprehensive income (loss)	(13,600,000)	8,500,000	17,800,000
Ending balance3	(44,300,000)	(24,500,000)	(33,000,000.0)
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	5,400,000
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]
Other comprehensive income (loss)	(64,100,000)	(3,000,000.0)	59,100,000
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(113,000,000.0)	(110,000,000.0)	(169,100,000)
Other comprehensive income (loss)	(64,100,000)	(3,000,000.0)	59,100,000
Ending balance3	(182,500,000)	$ (113,000,000.0)	$ (110,000,000.0)
Retained Earnings [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	(5,400,000)
Retained Earnings [Member] | Interest Rate Swap [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	$ (800,000)