Post Retirement Benefit Plans - Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Components of net periodic benefit costs:
Service cost	$ 5.5	$ 6.5	$ 8.1
Interest cost	$ 5.2	$ 1.0	$ 0.5
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Cost of Revenue	Cost of Revenue	Cost of Revenue
Expected return on plan assets	$ (4.4)	$ (1.7)	$ (1.8)
Settlement (gain) loss recognized	$ 0.0	$ (0.3)	$ 0.1
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Settlement Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Cost of Revenue	Cost of Revenue	Cost of Revenue
Amortization of prior service (credit) cost	$ (0.8)	$ (0.2)	$ 0.9
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Amortization of Prior Service Cost (Credit), Statement of Income or Comprehensive Income [Extensible Enumeration]	Cost of Revenue	Cost of Revenue	Cost of Revenue
Amortization of actuarial losses	$ 0.1	$ 2.2	$ 2.6
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Amortization of Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Cost of Revenue	Cost of Revenue	Cost of Revenue
Net periodic benefit costs	$ 5.6	$ 7.5	$ 10.4