Classification of Net Deferred Tax Assets in Balance Sheet (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Balance Sheet Classification of Deferred Income Tax Assets and Liabilities [Line Items]
Current net deferred tax assets	$ 4.0	$ 4.8
Current valuation allowance	(14.6)	(7.5)
Total current deferred tax liability	(10.6)	(2.7)
Long-term net deferred tax asset	81.4	75.3
Long-term valuation allowance	(117.2)	(116.3)
Long-term net deferred tax liability	$ (35.8)	$ (41.0)

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards expected to be realized or consumed within one year or operating cycle, if longer.

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Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards, net of deferred tax liability attributable to taxable temporary differences expected to be realized or consumed within one year or operating cycle, if longer.

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Amount of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards expected to be realized or consumed within one year or operating cycle, if longer.

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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized expected to be realized or consumed after one year (or the normal operating cycle, if longer).

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