Retirement Benefits - Schedule of Fair Value Measurements (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 3.1	$ 203.0
Quoted Prices in Active  Market (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	7.2
Significant Other Observable  Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Assets Measured at Net Asset Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3.1	195.8
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		4.2
Cash and cash equivalents | Quoted Prices in Active  Market (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		4.2
Cash and cash equivalents | Significant Other Observable  Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0.0
Cash and cash equivalents | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0.0
Cash and cash equivalents | Assets Measured at Net Asset Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0.0
Fixed income funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		178.3
Fixed income funds | Quoted Prices in Active  Market (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0.0
Fixed income funds | Significant Other Observable  Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0.0
Fixed income funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0.0
Fixed income funds | Assets Measured at Net Asset Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		178.3
U.S. equity funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		12.4
U.S. equity funds | Quoted Prices in Active  Market (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		3.0
U.S. equity funds | Significant Other Observable  Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0.0
U.S. equity funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0.0
U.S. equity funds | Assets Measured at Net Asset Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		9.4
International equity funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.5	5.7
International equity funds | Quoted Prices in Active  Market (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
International equity funds | Significant Other Observable  Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
International equity funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
International equity funds | Assets Measured at Net Asset Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.5	5.7
Balanced funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2.6	2.4
Balanced funds | Quoted Prices in Active  Market (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Balanced funds | Significant Other Observable  Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Balanced funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Balanced funds | Assets Measured at Net Asset Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 2.6	$ 2.4