Retirement Plans and Other Postretirement Benefits - Components of Net Periodic Cost, Changes in Plan Assets and Benefit Obligations, and AOCI Impacts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan
Service cost:
Benefit accrual	$ 0.0	$ 0.0	$ 0.0
Other expenses	0.6	0.7	0.7
Interest cost	0.5	0.7	1.0
Expected return on plan assets	(0.9)	(1.0)	(1.3)
Settlement loss	0.0	0.5	0.0
Amortization of:
Prior service cost	0.0	0.0	0.0
Actuarial loss	0.4	0.3	0.3
Net periodic pension expense	0.6	1.2	0.7
Changes in plan assets and benefit obligations included in other comprehensive income (loss):
Prior service cost	0.0	0.0	0.0
Net actuarial loss (gain)	(0.2)	0.3	(1.8)
Amortization of:
Prior service cost	0.0	0.0	0.0
Actuarial loss	(0.4)	(0.8)	(0.3)
Total recognized in other comprehensive income (loss)	$ (0.6)	$ (0.5)	$ (2.1)
Weighted average assumptions used to determine expense:
Discount rate	2.08%	3.10%	4.20%
Expected return on plan assets	4.74%	4.80%	5.75%
Weighted average assumptions used to determine benefit obligations as of December 31:
Discount rate	2.57%	2.08%	3.10%
Expected return on plan assets	4.74%	4.80%	5.75%
Supplemental Defined Benefit Plans
Service cost:
Benefit accrual	$ 0.0	$ 0.0	$ 0.0
Other expenses	0.0	0.0	0.0
Interest cost	0.3	0.5	0.6
Expected return on plan assets	0.0	0.0	0.0
Settlement loss	0.0	0.0	0.0
Amortization of:
Prior service cost	0.0	0.0	0.0
Actuarial loss	0.4	0.3	0.3
Net periodic pension expense	0.7	0.8	0.9
Changes in plan assets and benefit obligations included in other comprehensive income (loss):
Prior service cost	0.0	0.0	0.0
Net actuarial loss (gain)	(0.2)	1.3	0.5
Amortization of:
Prior service cost	0.0	0.0	0.0
Actuarial loss	(0.4)	(0.3)	(0.2)
Total recognized in other comprehensive income (loss)	$ (0.6)	$ 1.0	$ 0.3
Weighted average assumptions used to determine expense:
Discount rate	2.08%	3.10%	4.20%
Weighted average assumptions used to determine benefit obligations as of December 31:
Discount rate	2.57%	2.08%	3.10%