Restructuring Costs - Additional Information (Detail) - Chemicals - Employee Severance $ in Millions	9 Months Ended	12 Months Ended
	Dec. 31, 2015 Employee	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Restructuring Cost And Reserve [Line Items]
Workforce reduction, number of individuals | Employee	160
Restructuring charges			$ 21.7
Restructuring charges paid		$ 4.1	15.9
Cost of sales
Restructuring Cost And Reserve [Line Items]
Restructuring charges			10.8
Selling, general and administrative Expense
Restructuring Cost And Reserve [Line Items]
Restructuring charges			$ 10.9