Restructuring Costs - Additional Information (Detail) - Chemicals $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2015 USD ($) Employee	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Restructuring Cost And Reserve [Line Items]
Restructuring charges	$ 21.1
Employee Severance
Restructuring Cost And Reserve [Line Items]
Workforce reduction, number of individuals | Employee	110
Restructuring charges	$ 21.1	$ 21.1
Accrued severance costs, expected date to be paid		Dec. 31, 2016
Employee Severance | Scenario Forecast
Restructuring Cost And Reserve [Line Items]
Future workforce reduction costs to be incurred			$ 0.1
Employee Severance | Cost of sales
Restructuring Cost And Reserve [Line Items]
Restructuring charges	10.7
Employee Severance | Selling, general and administrative Expense
Restructuring Cost And Reserve [Line Items]
Restructuring charges	$ 10.4