Employee Benefits - Summary of Components of Net Periodic Postretirement Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Total net periodic postretirement benefit cost	$ 8.4	$ 5.6	$ 4.1
Salaried VEBA
Defined Benefit Plan Disclosure [Line Items]
Service cost		0.1
Interest cost	2.9	1.9
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	3.8	5.8	4.1
Interest cost	1.3	0.6	0.5
Expected return on plan assets	(1.1)	(0.9)	(0.4)
Amortization of prior service cost	0.4
Amortization of net actuarial loss (gain)			0.1
Total net periodic postretirement benefit cost	4.4	5.5	4.3
Other Postretirement Benefits Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	1.1	1.6	1.1
Interest cost	3.4	2.2	1.7
Amortization of net actuarial loss (gain)	(1.1)
Total net periodic postretirement benefit cost	3.4	3.8	2.8
Postretirement Health Coverage | Salaried VEBA
Defined Benefit Plan Disclosure [Line Items]
Service cost		0.1	0.1
Interest cost	2.9	1.9	1.5
Expected return on plan assets	(2.2)	(3.1)	(3.1)
Amortization of prior service cost	4.9	4.9	3.5
Amortization of net actuarial loss (gain)			0.3
Total net periodic postretirement benefit cost	$ 5.6	$ 3.8	$ 2.3