Supplemental Balance Sheet Information - USD ($)	Sep. 30, 2025	Sep. 30, 2024
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid Expense, Current	$ 78,400,000	$ 76,400,000
Value Added Tax Receivable, Current	43,700,000	40,000,000.0
Income Taxes Receivable, Current	13,300,000	14,700,000
Other Assets, Current	11,900,000	9,100,000
Other current assets	147,300,000	140,200,000
Other Liabilities, Current [Abstract]
Accrued Advertising, Current	26,200,000	26,300,000
Accrued Trade Allowance, Current	29,600,000	28,700,000
Employee-related Liabilities, Current	53,100,000	78,600,000
Accrued Income Taxes, Current	20,300,000	13,600,000
Reserve for Sales Returns, Current	42,800,000	50,300,000
Restructuring reserve	16,700,000	21,400,000
Interest Payable, Current	24,700,000	24,700,000
Other Accrued Liabilities, Current	102,900,000	76,200,000
Other current liabilities	316,300,000	319,800,000
Other Liabilities, Noncurrent [Abstract]
Liability, Defined Benefit Plan, Noncurrent	32,700,000	45,600,000
Other Accrued Liabilities, Noncurrent	102,900,000	129,400,000
Other Liabilities, Noncurrent	$ 135,600,000	$ 175,000,000.0