Stock-Based Compensation - Stock Options Outstanding (Detail) (USD $)	3 Months Ended
Mar. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Outstanding Shares, Beginning Balance	393,500
Granted, Shares	0
Exercised, Shares	81,000
Forfeited or canceled, Shares	5,500
Outstanding Shares, Ending Balance	307,000
Exercisable, Shares	302,000
Outstanding, Weighted Average Exercise Price, Beginning Balance	$ 8.49
Granted, Weighted Average Exercise Price	$ 0
Exercised, Weighted Average Exercise Price	$ 9.73
Forfeited or canceled, Weighted Average Exercise Price	$ 2.71
Outstanding, Weighted Average Exercise Price, Ending Balance	$ 8.35
Exercisable, Weighted Average Exercise Price	$ 8.27

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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

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

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-Section 50

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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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

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- Definition

For presentations that combine terminations, 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 or that expired.

+ References

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

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No definition available.

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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

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(1)(b)

-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 can acquire the shares reserved for issuance under the stock option plan.

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

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

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