Income Taxes - Reconciliations of Gross Unrecognized Tax Benefits (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	$ 53.4	$ 26.5	$ 24.3
Gross increases for tax positions in prior periods	12.2	2.2	2.1
Gross decreases for tax positions in prior periods	(0.6)	(0.6)	(0.2)
Gross increases based on tax positions related to the current year	2.7	13.6	3.2
Gross decreases related to settlements with taxing authorities	(5.1)	(13.2)	(2.5)
Reductions due to statute expiration	(1.8)	(0.4)	(0.4)
Gross increases due to acquisitions	0	25.3	0
Ending balance	$ 60.8	$ 53.4	$ 26.5

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The gross amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns as of the balance sheet date.

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-Name Accounting Standards Codification

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The gross amount of decreases in unrecognized tax benefits resulting from tax positions taken in prior period tax returns, excluding amounts pertaining to examined tax returns.

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The gross amount of decreases in unrecognized tax benefits resulting from settlements with taxing authorities.

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Gross amount of increases in unrecognized tax benefits resulting from acquisitions.

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The gross amount of increases in unrecognized tax benefits resulting from tax positions that have been or will be taken in the tax return for the current period, excluding amounts pertaining to examined tax returns.

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The gross amount of decreases in unrecognized tax benefits resulting from lapses of the applicable statutes of limitations.

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