Income Taxes - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Tax [Line Items]
Valuation allowance	$ 9.2	$ 10.4
Deferred tax assets, valuation allowances	15.7	17.8
Retained Earnings (Accumulated Deficit)	1,929.3	1,714.0
Unrecognized tax benefits that would impact effective tax rate	8.7	12.1	15.0
Unrecognized tax benefits that would impact balance sheet tax accounts	0.4	1.0	9.6
Reasonably possible decrease in liabilities for uncertain income tax positions	(3.1)
Reasonably possible change in other uncertain tax positions, description	Of this amount, $0.1 million would result in adjustments to balance sheet tax accounts, primarily deferred taxes and would not affect the effective tax rate.
Reasonably possible change in other uncertain tax positions	0.1
Interest expense associated with uncertain tax positions	0.3	1.9	4.2
Accrued interest expense associated with uncertain tax positions	0.4	0.7
Quimica Geral Do Nordeste Sa
Income Tax [Line Items]
Deferred tax assets, valuation allowances	6.5	7.4
Foreign Tax Authority
Income Tax [Line Items]
Loss carryforward	36.3
Expire Through December 31, 2018 | Foreign Tax Authority
Income Tax [Line Items]
Loss carryforward subject to expiration	9.8
Permanently Reinvested Foreign
Income Tax [Line Items]
Retained Earnings (Accumulated Deficit)	242.2
Reversal Of Income Tax Expense
Income Tax [Line Items]
Tax adjustments from settlement and lapse of applicable statutes of limitation	3.3	3.7	4.0
Reversal Of Pretax Interest Expense
Income Tax [Line Items]
Tax adjustments from settlement and lapse of applicable statutes of limitation	$ 0.2	$ 1.6	$ 3.0