Investment in TiO2 Manufacturing Joint Venture and Other Assets - Components of Net Capitalized Permit Costs (Detail) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Other Noncurrent Assets [Line Items]
Net capitalized permit costs	$ 48.1	$ 53.2
Permits Subject to Amortization
Other Noncurrent Assets [Line Items]
Net capitalized permit costs	47.3	53.2
Permits Not Subject to Amortization
Other Noncurrent Assets [Line Items]
Net capitalized permit costs	0.8
LLRW License - (expires in 2024) | Permits Subject to Amortization
Other Noncurrent Assets [Line Items]
Net capitalized permit costs	44.7	49.6
Byproduct License - (expires in 2018) | Permits Subject to Amortization
Other Noncurrent Assets [Line Items]
Net capitalized permit costs	2.5	3.5
Other - (expires 2015 - 2024) | Permits Subject to Amortization
Other Noncurrent Assets [Line Items]
Net capitalized permit costs	$ 0.1	$ 0.1