Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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- Definition

Face (par) amount of debt instrument at time of issuance.

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- Definition

Incremental percentage increase (decrease) in the stated rate on a debt instrument.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Debt (Private Placement Notes) (Details) - Unsecured debt $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2020 EUR (€)	Mar. 31, 2020	Dec. 31, 2019 USD ($)	Oct. 31, 2013 EUR (€)	Jun. 30, 2012 EUR (€)
Debt Instrument [Line Items]
Debt instrument, face amount \| €					€ 355,000,000.0	€ 325,000,000.0
5.00% Notes due 2020
Debt Instrument [Line Items]
Interest rate, stated percentage	5.00%	5.00%	5.00%	5.00%
Long-term Debt, Gross \| $	$ 0.0			$ 224.6
3.40% Notes due 2022
Debt Instrument [Line Items]
Debt instrument, face amount \| €						€ 150,000,000.0
Interest rate, stated percentage	3.40%	3.40%	3.40%	3.40%		3.40%
Long-term Debt, Gross \| $	$ 184.0			$ 168.5
4.00% Notes due 2027
Debt Instrument [Line Items]
Debt instrument, face amount \| €						€ 75,000,000.0
Interest rate, stated percentage	4.00%	4.00%	4.00%	4.00%		4.00%
Long-term Debt, Gross \| $	$ 92.0			$ 84.2
4.00% Notes due 2032
Debt Instrument [Line Items]
Debt instrument, face amount \| €						€ 100,000,000.0
Interest rate, stated percentage	4.00%	4.00%	4.00%	4.00%		4.00%
Long-term Debt, Gross \| $	$ 122.7			$ 112.3
3.75% Notes due 2033
Debt Instrument [Line Items]
Debt instrument, face amount \| €					€ 100,000,000.0
Interest rate, stated percentage	3.75%	3.75%	3.75%	3.75%	3.75%
Long-term Debt, Gross \| $	$ 122.7			$ 112.3
3.15% Notes due 2023
Debt Instrument [Line Items]
Debt instrument, face amount \| €					€ 130,000,000.0
Interest rate, stated percentage	3.15%	3.15%	3.15%	3.15%	3.15%
Long-term Debt, Gross \| $	$ 159.5			$ 146.0
3.15% Notes due 2023
Debt Instrument [Line Items]
Debt instrument, face amount \| €					€ 125,000,000.0
Interest rate, stated percentage	3.15%	3.15%	3.15%	3.15%	3.15%
Long-term Debt, Gross \| $	$ 153.4			$ 140.4
Notes due 2025 4.50%
Debt Instrument [Line Items]
Interest rate, stated percentage	4.50%	4.50%
Long-term Debt, Gross	$ 245.4	€ 200,000,000		$ 0.0
Debt Instrument, Interest Rate, Increase (Decrease)	5.75%