Pension Plans and Postretirement Benefit Plan - Additional Information (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2020 USD ($)
Pension Benefits
Net periodic benefit cost for pension plans and the postretirement benefit plan
Employer contributions	$ 0.1	$ 0.3
Estimated future employer contributions in current fiscal year	0.4	0.4
Postretirement Benefits
Net periodic benefit cost for pension plans and the postretirement benefit plan
Employer contributions	0.3	0.8
Estimated future employer contributions in current fiscal year	$ 1.0	$ 1.0