Stock Based Compensation - Summary of Activity and Various Other Information Relative to Stock Options (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Outstanding at beginning of period, Common Shares	1,914
Granted, Common Shares
Exercised, Common Shares	(1,073)
Expired, Common Shares
Forfeited, Common Shares	(4)
Outstanding at end of period, Common Shares	837
Exercisable at end of period, Common Shares	594
Outstanding at beginning of period, Weighted-Average Exercise Price	$ 4.29
Granted, Weighted-Average Exercise Price
Exercised, Weighted-Average Exercise Price	$ 3.15
Expired, Weighted-Average Exercise Price
Forfeited, Weighted-Average Exercise Price	$ 6.11
Outstanding at end of period, Weighted-Average Exercise Price	$ 5.73
Exercisable at end of period, Weighted-Average Exercise Price	$ 5.06
Outstanding at end of period, Aggregate Intrinsic Value	$ 22,514
Exercisable at end of period, Aggregate Intrinsic Value	$ 16,375

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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.

+ References

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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Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements.

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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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Net 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 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 of the plan that expired.

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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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