Discontinued Operations - Major Class of Assets and Liabilities Related to Discontinued Operations (Detail) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Property, plant and equipment, net		$ 29.6
Non-current liabilities		3.8
Aromatics [Member] | Discontinued Operations Disposed of by Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Receivables, net	$ 7.0	36.4
Inventories	1.0	31.8
Property, plant and equipment, net		29.6
Total assets	8.0	97.8
Accounts payable	5.9	30.9
Accrued compensation		0.3
Other accrued liabilities	2.4	1.4
Non-current liabilities		3.8
Total liabilities	8.3	36.4
Net assets (liabilities)	$ (0.3)	$ 61.4