Stock-Based Compensation - Summary of Company's Stock Option Plan Activity (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Options outstanding, Beginning balance			887,000
Number of Shares, Granted	0	0	100,000
Number of Shares, Exercised			(98,000)
Number of Shares, Forfeited			0
Number of Shares, Options outstanding, Ending balance	889,000		889,000
Number of Shares, Options exercisable	561,000		561,000
Number of Shares, Available for grant	988,000		988,000
Weighted Average Price Per Share, Options outstanding, Beginning balance			$ 8.66
Weighted Average Price Per Share, Granted			$ 16.73
Weighted Average Price Per Share, Exercised			$ 5.46
Weighted Average Price Per Share, Forfeited			$ 0
Weighted Average Price Per Share, Options outstanding, Ending balance	$ 9.92		$ 9.92
Weighted Average Price Per Share, Option exercisable	$ 6.64		$ 6.64
Weighted Average Remaining Contractual Life (Years), Option outstanding			6 years
Weighted Average Remaining Contractual Life (Years), Option exercisable			4 years 2 months 12 days
Aggregate Intrinsic Value, Option outstanding	$ 13,403		$ 13,403
Aggregate Intrinsic Value, Option exercisable	$ 10,296		$ 10,296

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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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.

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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)

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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.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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.

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

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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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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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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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