Stock-Based Compensation - Summary of Share-Based Option Activity (Detail) (USD $)	9 Months Ended
Sep. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Outstanding	8,744,649
Shares Granted	7,992,285
Shares Canceled	(8,296,470)
Shares Outstanding	8,440,464
Shares Vested and expected to vest at September	7,033,200
Shares Exercisable at September 30, 2012	1,404,145
Weighted Average Exercise Price Outstanding	$ 38.15
Weighted Average Exercise Price Granted	$ 8.47
Weighted Average Exercise Price Canceled	$ 31.35
Weighted Average Exercise Price Outstanding	$ 10.71
Weighted Average Exercise Price Vested and expected to vest at September 30, 2012	$ 10.71
Weighted Average Exercise Price Exercisable at September 30, 2012	$ 10.69

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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.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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- Definition

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

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

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-Name Accounting Standards Codification

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- Definition

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

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Definition

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

+ References

No definition available.

+ Details

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- Definition

The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

+ References

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

-Publisher FASB

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- Definition

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

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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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

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

-Publisher FASB

-Name Accounting Standards Codification

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- Definition

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

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

+ References

No definition available.

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Weighted average price at which grantees can acquire the shares reserved for issuance on stock options awarded.

+ References

No definition available.

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