Fair Value Measurement - Narrative (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Accounts receivable, net	$ 798.3		$ 634.7
Accounts receivable, allowances	11.6		12.5
Increase (decrease) in accounts receivable, allowances	(0.9)
Available for sale debt securities	58.1		57.7
Available for sale debt securities, amortized cost	57.2		56.4
Available for sale debt securities, allowance for credit losses	0.0
Available for sale debt securities, unrealized losses	0.1		0.1
Available for sale debt securities with unrealized losses, fair value	11.4		6.1
Trading securities	23.9		22.7
Purchase of trading securities related to deferred compensation plans	2.5	$ 2.7
Proceeds from securities sold	3.0	$ 2.0
Long-term debt	1,434.9		1,436.9
Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	1,434.9		1,436.9
Long-term debt, fair value	$ 1,540.0		$ 1,569.5

Amount of allowance for credit loss on accounts receivable, classified as current.

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading) and investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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