Stock-Based Compensation - Option Activity under the Company's Stock Option Plans (Detail) - USD ($)	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Number of Shares
Outstanding beginning of period (in shares)	67,488
Exercised (in shares)	(35,782)
Outstanding at end of period (in shares)	31,706	67,488
Options exercisable at year-end (in shares)	31,706
Weighted Average Exercise Price
Outstanding beginning of period (in usd per share)	$ 8.28
Exercised (in usd per share)	8.75
Outstanding end of period (in usd per share)	7.76	$ 8.28
Options exercisable at year-end (in usd per share)	$ 7.76
Weighted Average Remaining Contractual Term (in Years)
Weighted average remaining contractual term (in years)	17 days	2 years 10 months 9 days
Options exercisable at year-end	17 days
Aggregate Intrinsic Value
Aggregate intrinsic value	$ 305,120	$ 440,483
Options exercisable at year-end	$ 305,120

Share Based Compensation Arrangement By Share Based Payment Award Intrinsic Value [Abstract]

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Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Remaining Term [Abstract]

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

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