Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2015	Dec. 31, 2014
Income Tax Contingency [Line Items]
Gross unrecognized tax benefits	$ 12.0	$ 14.9
Unrecognized tax benefits that would impact effective tax rate	12.0
Gross unrecognized tax benefits net decrease	(2.9)
Minimum [Member]
Income Tax Contingency [Line Items]
Gross unrecognized tax benefits balance may decrease within the next twelve months	0.0
Maximum [Member]
Income Tax Contingency [Line Items]
Gross unrecognized tax benefits balance may decrease within the next twelve months	$ 1.7

Amount of decrease reasonably possible in the next twelve months for the unrecognized tax benefit.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 15

-Subparagraph (d)(3)

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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

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 15A

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6907707&loc=SL6600010-109319

Reference 2: 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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The net amount of all increases and decreases in unrecognized tax benefits for the period.

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The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

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