Fair Value - Recurring Fair Value Measures (Details) - USD ($) $ in Millions		Jun. 30, 2023		Dec. 31, 2022
Investments [Abstract]
Available-for-sale Securities, Debt Maturities, within One Year, Fair Value		$ 1.2
Available-for-sale Securities, Debt Maturities, After One Year Through Three Years, Fair Value		2.7
Available-for-sale Securities, Debt Maturities, After Three Years Through Five Years, Fair Value		1.4
Available-for-sale Securities, Debt Maturities, After Five Years, Fair Value		0.4
Recurring Fair Value Measures [Member]
Investments [Abstract]
Available-for-sale - Equity Securities	[1]	8.4		$ 7.7
Available-for-sale – Corporate and Governmental Debt Securities (b)	[1]	5.7	[2]	5.7
Cash Equivalents	[1]	5.8		4.2
Total Fair Value of Assets		19.9		17.6
Liabilities [Abstract]
Deferred Compensation	[3]	16.2		15.0
Total Fair Value of Liabilities		16.2		15.0
Recurring Fair Value Measures [Member] | Level 1 [Member]
Investments [Abstract]
Available-for-sale - Equity Securities	[1]	8.4		7.7
Available-for-sale – Corporate and Governmental Debt Securities (b)	[1]	0.0	[2]	0.0
Cash Equivalents	[1]	5.8		4.2
Total Fair Value of Assets		14.2		11.9
Liabilities [Abstract]
Deferred Compensation	[3]	0.0		0.0
Total Fair Value of Liabilities		0.0		0.0
Recurring Fair Value Measures [Member] | Level 2 [Member]
Investments [Abstract]
Available-for-sale - Equity Securities	[1]	0.0		0.0
Available-for-sale – Corporate and Governmental Debt Securities (b)	[1]	5.7	[2]	5.7
Cash Equivalents	[1]	0.0		0.0
Total Fair Value of Assets		5.7		5.7
Liabilities [Abstract]
Deferred Compensation	[3]	16.2		15.0
Total Fair Value of Liabilities		16.2		15.0
Recurring Fair Value Measures [Member] | Level 3 [Member]
Investments [Abstract]
Available-for-sale - Equity Securities	[1]	0.0		0.0
Available-for-sale – Corporate and Governmental Debt Securities (b)	[1]	0.0	[2]	0.0
Cash Equivalents	[1]	0.0		0.0
Total Fair Value of Assets		0.0		0.0
Liabilities [Abstract]
Deferred Compensation	[3]	0.0		0.0
Total Fair Value of Liabilities		$ 0.0		$ 0.0

[1] Included in Other Non-Current Assets on the Consolidated Balance Sheet.

[2] As of June 30, 2023, the aggregate amount of available-for-sale corporate and governmental debt securities maturing in one year or less was $1.2 million, in one year to less than three years was $2.7 million, in three years to less than five years was $1.4 million and in five or more years was $0.4 million.

[3] Included in Other Non-Current Liabilities on the Consolidated Balance Sheet.