Fair Value Measurements - Schedule of Fair Value, Assets and Liabilities Measure on Recurring Basis (Details) - Fair Value, Recurring - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Financial assets:
Total financial assets	$ 22.4	$ 19.5
Financial liabilities:
Derivative financial instruments		0.1
Deferred compensation programs' liabilities	6.0	5.5
Total financial liabilities	6.0	5.6
Corporate bonds
Financial assets:
Trading debt securities:	3.6	3.4
Agency bonds
Financial assets:
Trading debt securities:	2.5	2.5
U.S. government securities
Financial assets:
Trading debt securities:	2.9	1.9
Asset-backed securities
Financial assets:
Trading debt securities:	5.5	4.0
Exchange traded funds
Financial assets:
Trading debt securities:	1.2	1.3
Mortgage backed securities
Financial assets:
Trading debt securities:	0.4	0.5
Other
Financial assets:
Trading debt securities:	0.6	0.7
Preferred stocks
Financial assets:
Trading equity securities:	0.3	0.3
Equity Funds
Financial assets:
Trading equity securities:	0.5	0.7
Supplemental Employee Retirement Plan and Non-Qualified Deferred Compensation Plan | Mutual Fund
Financial assets:
Trading equity securities:	4.9	4.2
Level 1
Financial assets:
Total financial assets	13.6	12.0
Financial liabilities:
Derivative financial instruments		0.0
Deferred compensation programs' liabilities	0.0	0.0
Total financial liabilities	0.0	0.0
Level 1 | Corporate bonds
Financial assets:
Trading debt securities:	3.6	3.4
Level 1 | Agency bonds
Financial assets:
Trading debt securities:	0.0	0.0
Level 1 | U.S. government securities
Financial assets:
Trading debt securities:	2.9	1.9
Level 1 | Asset-backed securities
Financial assets:
Trading debt securities:	0.0	0.0
Level 1 | Exchange traded funds
Financial assets:
Trading debt securities:	1.2	1.3
Level 1 | Mortgage backed securities
Financial assets:
Trading debt securities:	0.0	0.0
Level 1 | Other
Financial assets:
Trading debt securities:	0.2	0.2
Level 1 | Preferred stocks
Financial assets:
Trading equity securities:	0.3	0.3
Level 1 | Equity Funds
Financial assets:
Trading equity securities:	0.5	0.7
Level 1 | Supplemental Employee Retirement Plan and Non-Qualified Deferred Compensation Plan | Mutual Fund
Financial assets:
Trading equity securities:	4.9	4.2
Level 2
Financial assets:
Total financial assets	8.8	7.5
Financial liabilities:
Derivative financial instruments		0.1
Deferred compensation programs' liabilities	6.0	5.5
Total financial liabilities	6.0	5.6
Level 2 | Corporate bonds
Financial assets:
Trading debt securities:	0.0	0.0
Level 2 | Agency bonds
Financial assets:
Trading debt securities:	2.5	2.5
Level 2 | U.S. government securities
Financial assets:
Trading debt securities:	0.0	0.0
Level 2 | Asset-backed securities
Financial assets:
Trading debt securities:	5.5	4.0
Level 2 | Exchange traded funds
Financial assets:
Trading debt securities:	0.0	0.0
Level 2 | Mortgage backed securities
Financial assets:
Trading debt securities:	0.4	0.5
Level 2 | Other
Financial assets:
Trading debt securities:	0.4	0.5
Level 2 | Preferred stocks
Financial assets:
Trading equity securities:	0.0	0.0
Level 2 | Equity Funds
Financial assets:
Trading equity securities:	0.0	0.0
Level 2 | Supplemental Employee Retirement Plan and Non-Qualified Deferred Compensation Plan | Mutual Fund
Financial assets:
Trading equity securities:	$ 0.0	$ 0.0