Discontinued Operations - Depreciation, Amortization and Capital Expenditures Associated with Discontinued Operations (Detail) - Aromatics [Member] - Discontinued Operations Disposed of by Sale [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Depreciation and amortization	$ 2.1	$ 2.8
Capital expenditures	$ 1.0	$ 1.7