Stock-Based Compensation - Summary of Stock Option Awards (Detail) - Employee Stock Option [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options outstanding at December 31, 2016 (shares)	1,154,658
Options granted (shares)	0	0	0
Options exercised (shares)	(171,747)
Options forfeited (shares)	(29,006)
Options outstanding at December 31, 2017 (shares)	953,905	1,154,658
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted Average Exercise Price, Outstanding, Balance (in usd per share)	$ 14.16
Weighted Average Exercise Price, Granted (in usd per share)	0.00
Weighted Average Exercise Price, Exercised (in usd per share)	12.05
Weighted Average Exercise Price, Forfeited (in usd per share)	12.73
Weighted Average Exercise Price, Outstanding, Balance (in usd per share)	14.58	$ 14.16
Weighted Average Exercise Price, Options exercisable at December 31, 2017 (in usd per share)	$ 14.58
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Options exercisable at December 31, 2017 (shares)	953,905
Weighted Average Remaining Contractual Life, Outstanding	4 years 2 months 12 days	4 years 10 months 24 days
Weighted Average Remaining Contractual Life, Options exercisable at December 31, 2017	4 years 2 months 12 days
Aggregate Intrinsic Value, Outstanding, Balance	$ 296	$ 4,350
Aggregate Intrinsic Value, Outstanding, Options exercisable at December 31, 2017	$ 296

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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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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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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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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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

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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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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 remaining contractual term for fully vested and expected to vest exercisable or convertible options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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

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