Income Taxes - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Mar. 31, 2013	Jun. 30, 2013	Jun. 30, 2012
Income Tax Disclosure [Abstract]
Company's effective tax rate		(13.50%)	145.70%
One-time non-deductible pre-tax expenses		$ 150.3
Non-taxable pre-tax income		15.0
Goodwill impairment		647.5
Reduction of uncertain tax positions	$ 3.9

A ratio calculated by dividing the reported amount of income tax expense attributable to continuing operations for the period by GAAP-basis pretax income from continuing operations.

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Loss recognized during the period that results from the write-down of goodwill after comparing the implied fair value of reporting unit goodwill with the carrying amount of that goodwill. Goodwill is assessed at least annually for impairment.

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