Financing Agreements - Narrative (Details) € in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 31, 2022 USD ($)	Mar. 31, 2021	Mar. 31, 2022 USD ($)	Mar. 31, 2021	Sep. 30, 2021 USD ($)	Mar. 31, 2022 EUR (€)	Jun. 16, 2020 USD ($)	Dec. 15, 2014 USD ($)
Debt instrument [Line Items]
Long-term debt	$ 1,214,000,000		$ 1,214,000,000		$ 1,212,900,000
Covenant terms, maximum ratio of indebtedness to earnings before interest, taxes, depreciation, and amortization					3.50
Covenant terms, minimum ratio of earnings before interest, taxes, depreciation, and amortization to interest expense					3.00
$900.0 revolving credit facility (excluding outstanding letters of credit)
Debt instrument [Line Items]
Long-term debt	0		0		$ 0
Letters of credit outstanding, amount	16,400,000		16,400,000
Line of credit facility, remaining borrowing capacity	$ 883,600,000		$ 883,600,000
Weighted-average interest rate	2.21%		2.28%
Weighted average facility fee	0.15%	0.24%	0.15%	0.27%
$900.0 revolving credit facility (excluding outstanding letters of credit) | Revolving Credit Facility
Debt instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 900,000,000.0		$ 900,000,000.0
Other Financing Agreements
Debt instrument [Line Items]
Line of credit facility, maximum borrowing capacity	405,200,000		405,200,000		411.5
Line of credit facility, amount utilized for bank guarantees	235,800,000		235,800,000		254.0
Other Financing Agreements | Letter of Credit
Debt instrument [Line Items]
Line of credit facility, maximum borrowing capacity | €						€ 175.0
$375.0 senior unsecured notes, net of discount (2)
Debt instrument [Line Items]
Debt instrument, face amount	375,000,000.0		375,000,000.0
Long-term debt	371,800,000		371,800,000		371,500,000
$400.0 senior unsecured notes (1)
Debt instrument [Line Items]
Debt instrument, face amount							$ 400,000,000.0
Long-term debt	396,400,000		396,400,000		395,800,000
$100.0 Series A Notes (4)
Debt instrument [Line Items]
Debt instrument, face amount								$ 100,000,000.0
Long-term debt	$ 99,800,000		$ 99,800,000		$ 99,800,000
Debt interest rate, percent								4.60%
L/G Facility Agreement Amendment
Debt instrument [Line Items]
Covenant terms, maximum ratio of indebtedness to earnings before interest, taxes, depreciation, and amortization					3.50
Covenant terms, minimum ratio of earnings before interest, taxes, depreciation, and amortization to interest expense					3.00