Supplemental Balance Sheet Information - Inventories (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Inventory, LIFO, Net [Abstract]
Raw materials	$ 57.1	$ 46.3
Work in process	27.4	30.4
Finished goods	62.0	49.5
Supplies and other	0.0	0.0
Inventory, gross	146.5	126.2
Excess of FIFO or weighted-average cost over LIFO cost	(7.6)	(9.9)
Inventories, net	138.9	116.3
Inventory, Non-LIFO, Net [Abstract]
Raw materials	3.0	2.9
Work in process	0.5	0.5
Finished goods	25.9	21.7
Supplies and other	5.8	4.5
Inventory, gross	35.2	29.6
Excess of FIFO or weighted-average cost over LIFO cost	(7.6)	(9.9)
Inventories, net	35.2	29.6
Inventory, Net [Abstract]
Raw materials	60.1	49.2
Work in process	27.9	30.9
Finished goods	87.9	71.2
Supplies and other	5.8	4.5
Inventory, gross	181.7	155.8
Excess of FIFO or weighted-average cost over LIFO cost	(7.6)	(9.9)
Inventories	$ 174.1	$ 145.9