Other Comprehensive Income (Loss) (Schedule of Changes in AOCL by Component) (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Sep. 30, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	$ 6,000,000.0
Other comprehensive income (loss)
Other Comprehensive Income (Loss), Net of Tax, Total	13,700,000	$ 11,400,000	$ 40,700,000	$ (29,700,000)	$ (29,700,000)
Accumulated other comprehensive loss
Beginning balance			1,726,100,000
Net activity	13,700,000	11,400,000	40,700,000	(29,700,000)	(29,700,000)
Ending balance	1,821,000,000.0		1,821,000,000.0		1,726,100,000
Income Tax Expense (Benefit)	11,300,000	26,300,000	43,300,000	39,000,000.0
Net Income (Loss) Attributable to Parent	49,200,000	93,900,000	195,100,000	180,600,000
Available-for-sale Securities and Hedges [Member]
Other comprehensive income (loss)
Prior to reclassification	6,900,000	(6,000,000.0)	29,000,000.0	(39,700,000)
Reclassification from	5,200,000	(2,900,000)	(13,700,000)	(2,400,000)
Pre-tax	1,700,000	(8,900,000)	15,300,000	(42,100,000)
Tax effect	500,000	2,200,000	(3,600,000)	9,700,000
Other Comprehensive Income (Loss), Net of Tax, Total	1,200,000	(6,700,000)	11,700,000	(32,400,000)
Accumulated other comprehensive loss
Beginning balance	(18,800,000)	(18,500,000)	(29,300,000)	7,200,000	7,200,000
Net activity	1,200,000	(6,700,000)	11,700,000	(32,400,000)
Ending balance	(17,600,000)	(25,200,000)	(17,600,000)	(25,200,000)	(29,300,000)
Net Income (Loss) Attributable to Parent	(3,900,000)	(2,100,000)	(10,500,000)	(1,800,000)
Foreign Currency Translation Adjustment [Member]
Other comprehensive income (loss)
Prior to reclassification	11,700,000	17,100,000	26,500,000	8,600,000
Reclassification from	0	0	0	0
Pre-tax	11,700,000	17,100,000	26,500,000	8,600,000
Tax effect	0	0	0	0
Other Comprehensive Income (Loss), Net of Tax, Total	11,700,000	17,100,000	26,500,000	8,600,000
Accumulated other comprehensive loss
Beginning balance	(95,900,000)	(153,900,000)	(110,700,000)	(145,400,000)	(145,400,000)
Net activity	11,700,000	17,100,000	26,500,000	8,600,000
Ending balance	(84,200,000)	(136,800,000)	(84,200,000)	(136,800,000)	(110,700,000)
Change in Pension and Postretirement Defined Benefit Plans [Member]
Other comprehensive income (loss)
Prior to reclassification	(100,000)	200,000	(300,000)	100,000
Reclassification from	1,200,000	1,400,000	3,700,000	(7,700,000)
Pre-tax	1,100,000	1,600,000	3,400,000	(7,600,000)
Tax effect	(300,000)	(600,000)	(900,000)	1,700,000
Other Comprehensive Income (Loss), Net of Tax, Total	800,000	1,000,000.0	2,500,000	(5,900,000)
Accumulated other comprehensive loss
Beginning balance	(38,500,000)	(51,200,000)	(40,200,000)	(44,300,000)	(44,300,000)
Net activity	800,000	1,000,000.0	2,500,000	(5,900,000)
Ending balance	(37,700,000)	(50,200,000)	(37,700,000)	(50,200,000)	(40,200,000)
Income Tax Expense (Benefit)	(300,000)	(600,000)	(900,000)	1,700,000
Change in Pension and Postretirement Defined Benefit Plans [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated other comprehensive loss
Net Income (Loss) Attributable to Parent	900,000	(800,000)	2,800,000	(6,000,000.0)
Accumulated Other Comprehensive Income (Loss) [Member]
Other comprehensive income (loss)
Prior to reclassification	18,500,000	11,300,000	55,200,000	(31,000,000.0)
Reclassification from	(4,000,000.0)	(1,500,000)	10,000,000.0	(10,100,000)
Pre-tax	14,500,000	9,800,000	45,200,000	(41,100,000)
Tax effect	(800,000)	1,600,000	(4,500,000)	11,400,000
Other Comprehensive Income (Loss), Net of Tax, Total	13,700,000	11,400,000	40,700,000	(29,700,000)
Accumulated other comprehensive loss
Beginning balance	(153,200,000)	(223,600,000)	(180,200,000)	(182,500,000)	(182,500,000)
Net activity	13,700,000	11,400,000	40,700,000	(29,700,000)
Ending balance	(139,500,000)	(212,200,000)	(139,500,000)	(212,200,000)	(180,200,000)
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
Other comprehensive income (loss)
Reclassification from	(5,200,000)	(2,900,000)	(13,700,000)	(2,400,000)
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent | Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated other comprehensive loss
Income Tax Expense (Benefit)	1,300,000	800,000	3,200,000	600,000
Foreign Exchange Forward [Member] | Available-for-sale Securities and Hedges [Member]
Other comprehensive income (loss)
Pre-tax	1,000,000.0	(800,000)	(200,000)	(1,000,000.0)
Other Comprehensive Income (Loss), Net of Tax, Total	700,000	(600,000)	(200,000)	(800,000)
Accumulated other comprehensive loss
Beginning balance	(1,200,000)	0	(300,000)	200,000	200,000
Net activity	700,000	(600,000)	(200,000)	(800,000)
Ending balance	(500,000)	(600,000)	(500,000)	(600,000)	(300,000)
Foreign Exchange Forward [Member] | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
Other comprehensive income (loss)
Tax effect	(300,000)	200,000	0	200,000
Interest Rate Swap [Member] | Available-for-sale Securities and Hedges [Member]
Other comprehensive income (loss)
Pre-tax	3,400,000	(4,600,000)	20,500,000	(43,000,000.0)
Other Comprehensive Income (Loss), Net of Tax, Total	2,600,000	(3,500,000)	15,800,000	(33,100,000)
Accumulated other comprehensive loss
Beginning balance	(22,500,000)	(34,800,000)	(35,700,000)	(5,200,000)	(5,200,000)
Net activity	2,600,000	(3,500,000)	15,800,000	(33,100,000)
Ending balance	(19,900,000)	(38,300,000)	(19,900,000)	(38,300,000)	(35,700,000)
Interest Rate Swap [Member] | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
Other comprehensive income (loss)
Prior to reclassification	7,400,000	(2,900,000)	31,200,000	(41,700,000)
Reclassification from	(4,000,000.0)	(1,700,000)	(10,700,000)	(1,300,000)
Tax effect	(800,000)	1,100,000	(4,700,000)	9,900,000
Accumulated other comprehensive loss
Income Tax Expense (Benefit)	1,000,000.0	400,000	2,500,000	300,000
Net Income (Loss) Attributable to Parent	(3,000,000.0)	(1,300,000)	(8,200,000)	(1,000,000.0)
Currency Swap [Member] | Available-for-sale Securities and Hedges [Member]
Accumulated other comprehensive loss
Beginning balance	4,900,000	16,300,000	6,700,000	12,200,000	12,200,000
Ending balance					$ 6,700,000
Currency Swap [Member] | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
Other comprehensive income (loss)
Prior to reclassification	(2,700,000)	(3,500,000)	(5,000,000.0)	1,900,000
Reclassification from	0	0	0	0
Tax effect	600,000	900,000	1,100,000	(400,000)
Foreign Exchange Contract [Member] | Available-for-sale Securities and Hedges [Member]
Other comprehensive income (loss)
Pre-tax	(2,700,000)	(3,500,000)	(5,000,000.0)	1,900,000
Other Comprehensive Income (Loss), Net of Tax, Total	(2,100,000)	(2,600,000)	(3,900,000)	1,500,000
Accumulated other comprehensive loss
Net activity	(2,100,000)	(2,600,000)	(3,900,000)	1,500,000
Ending balance	2,800,000	13,700,000	2,800,000	13,700,000
Foreign Exchange | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
Other comprehensive income (loss)
Prior to reclassification	2,200,000	400,000	2,800,000	100,000
Reclassification from	(1,200,000)	(1,200,000)	(3,000,000.0)	(1,100,000)
Accumulated other comprehensive loss
Income Tax Expense (Benefit)	300,000	400,000	700,000	300,000
Net Income (Loss) Attributable to Parent	$ (900,000)	$ (800,000)	$ (2,300,000)	$ (800,000)