Fair Value Measurements (Financial Instruments Recorded at Fair Value) (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Cash and cash equivalents	$ 1,868.2	$ 1,957.2
Deferred compensation asset	0.5	0.5
Deferred compensation obligation	0.5	0.5
0.0 Percent Convertible Note
Debt Issuance Costs, Net	20.5	21.3
Fair Value, Inputs, Level 1 [Member]
Deferred compensation asset	0.5	0.5
Deferred compensation obligation	0.5	0.5
Fair Value, Inputs, Level 2 [Member]
Cash and cash equivalents	0.0	0.0
Deferred compensation asset	0.0	0.0
Deferred compensation obligation	0.0	0.0
Fair Value, Inputs, Level 3 [Member]
Cash and cash equivalents	0.0	0.0
Deferred compensation asset	0.0	0.0
Deferred compensation obligation	$ 0.0	$ 0.0

Fair value portion of the amount that could be realized under a life insurance contract or contracts owned by the entity, commonly known as corporate-owned life insurance (COLI) or bank-owned life insurance (BOLI).