Supplemental Balance Sheet Information - Inventories (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Inventory, LIFO, Net [Abstract]
Raw materials	$ 50.4	$ 46.3
Work in process	28.8	30.4
Finished goods	53.4	49.5
Supplies and other	0.0	0.0
Inventory, gross	132.6	126.2
Excess of FIFO or weighted-average cost over LIFO cost	(6.9)	(9.9)
Inventories, net	125.7	116.3
Inventory, Non-LIFO, Net [Abstract]
Raw materials	2.9	2.9
Work in process	0.4	0.5
Finished goods	20.1	21.7
Supplies and other	4.0	4.5
Inventory, gross	27.4	29.6
Inventories, net	27.4	29.6
Inventory, Net [Abstract]
Raw materials	53.3	49.2
Work in process	29.2	30.9
Finished goods	73.5	71.2
Supplies and other	4.0	4.5
Inventory, gross	160.0	155.8
Excess of FIFO or weighted-average cost over LIFO cost	(6.9)	(9.9)
Inventories	$ 153.1	$ 145.9