Supplemental Balance Sheet Information - Inventories (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Inventory, LIFO, Net [Abstract]
Raw materials	$ 50.7	$ 49.7
Work in process	52.8	46.1
Finished goods	144.2	165.8
Supplies and other	0.1	0.1
Inventory, gross	247.8	261.7
Excess of FIFO or weighted-average cost over LIFO cost	(9.3)	(17.6)
Inventories, net	238.5	244.1
Inventory, Non-LIFO, Net [Abstract]
Raw materials	0.9	1.1
Work in process	0.7	0.1
Finished goods	45.7	46.3
Supplies and other	12.9	11.6
Inventory, gross	60.2	59.1
Inventories, net	60.2	59.1
Inventory, Net [Abstract]
Raw materials	51.6	50.8
Work in process	53.5	46.2
Finished goods	189.9	212.1
Supplies and other	13.0	11.7
Inventory, gross	308.0	320.8
Excess of FIFO or weighted-average cost over LIFO cost	(9.3)	(17.6)
Inventories, net	$ 298.7	$ 303.2