Leases - Balance sheet by asset category (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Operating lease ROU Asset	$ 46.9	$ 52.6
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Other Assets, Noncurrent	Other Assets, Noncurrent
Property, plant and equipment, gross	$ 608.8	$ 608.6
Less: Accumulated depreciation	(408.1)	(396.3)
Property, plant and equipment, net	200.7	212.3	$ 200.0
Finance Leased Asset
Lessee, Lease, Description [Line Items]
Less: Accumulated depreciation	(4.2)	(10.8)
Property, plant and equipment, net	3.2	12.9
Finance Leased Real Estate
Lessee, Lease, Description [Line Items]
Property, plant and equipment, gross		15.8
Finance Leased Automobile
Lessee, Lease, Description [Line Items]
Property, plant and equipment, gross	0.1	0.1
Finance Leased Machinery and Equipment
Lessee, Lease, Description [Line Items]
Property, plant and equipment, gross	7.3	7.8
Real Estate
Lessee, Lease, Description [Line Items]
Operating lease ROU Asset	43.4	48.1
Automobile
Lessee, Lease, Description [Line Items]
Operating lease ROU Asset	2.2	3.2
Machinery and equipment.
Lessee, Lease, Description [Line Items]
Operating lease ROU Asset	$ 1.3	$ 1.3