Inventories, Net - Inventories, Net (Detail) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Inventory [Line Items]
Raw materials	$ 83.0	$ 79.4
Work in process	41.1	43.2
Finished products	232.2	256.4
Supplies	62.1	64.0
Total	418.4	443.0
Chemicals
Inventory [Line Items]
Raw materials	79.5	76.0
Work in process	30.8	32.9
Finished products	229.9	253.2
Component Products
Inventory [Line Items]
Raw materials	3.5	3.4
Work in process	10.3	10.3
Finished products	$ 2.3	$ 3.2