Income Taxes - Schedule Of Gross Unrecognized Income Tax Benefits (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Beginning balance		$ 74.0us-gaap_UnrecognizedTaxBenefits	$ 88.0us-gaap_UnrecognizedTaxBenefits	$ 98.1us-gaap_UnrecognizedTaxBenefits
Increases related to tax positions taken during the current year		22.3	22.8	17.5
Increases related to tax positions taken during a prior year			0	12.9
Decreases related to tax positions taken during a prior year		0	(1.5)	(8.3)
Decreases related to settlements with tax authorities	(20.3)	(19.1)	(6.0)	0
Decreases related to expiration of statute of limitations		(1.7)	(29.3)	(32.2)
Ending balance	$ 75.5us-gaap_UnrecognizedTaxBenefits	$ 75.5us-gaap_UnrecognizedTaxBenefits	$ 74.0us-gaap_UnrecognizedTaxBenefits	$ 88.0us-gaap_UnrecognizedTaxBenefits

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Amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Unrecognized Tax Benefit

-URI http://asc.fasb.org/extlink&oid=6527854

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-Publisher FASB

-Name Accounting Standards Codification

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Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

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Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

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-Name Accounting Standards Codification

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Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

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Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations.

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