Stock-Based Compensation - Summary of Share-Based Option Activity (Detail) (USD $)	9 Months Ended
Sep. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Shares Outstanding, Beginning of Period	8,478,148
Shares Granted	550,812
Shares Exercised	(127,660)
Shares Canceled	(345,107)
Shares Outstanding, End of Period	8,556,193
Shares Vested and expected to vest at September 30, 2013	6,753,926
Shares Exercisable at September 30, 2013	2,301,361
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted Average Exercise Price Outstanding, Beginning of Period	$ 12.22
Weighted Average Exercise Price Granted	$ 13.65
Weighted Average Exercise Price Exercised	$ 8.39
Weighted Average Exercise Price Canceled	$ 12.05
Weighted Average Exercise Price Outstanding, End of Period	$ 12.38
Weighted Average Exercise Price Vested and expected to vest at September 30, 2013	$ 12.44
Weighted Average Exercise Price Exercisable at September 30, 2013	$ 15.58

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)(iii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

+ References

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

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-Subparagraph (c)(1)(iv)(3)

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Gross number of share options (or share units) granted during the period.

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Number of options outstanding, including both vested and non-vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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As of the balance sheet date, the number of shares into which fully vested and expected to vest stock options outstanding can be converted under the option plan.

+ References

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As of the balance sheet date, the weighted-average exercise price for outstanding stock options that are fully vested or expected to vest.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Number of share options (or share units) exercised during the current period.

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