Number Of Companies Used For Estimation Of Expected Volatility

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Share based compensation arrangement by share based payment award equity instruments other than options increase in annual award.

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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Restricted Stock and Stock Options - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2020 USD ($) Company shares	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($) shares	Dec. 31, 2013 USD ($)
2005 Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Duration for Stock option grants exercisable	10 years
Expiration of stock option	90 days
Unexercised portion of stock option remains exercisable	1 year
Number of companies used for the estimation of expected volatility \| Company	6
Dividend yield assumed	0.00%
Cash dividends paid \| $					$ 0
Compensation expense \| $	$ 0	$ 0	$ 12,000
2005 Incentive Plan [Member] \| Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock outstanding	0
2012 Equity and Incentive Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized under incentive plan	500,000
Common stock granted	23,207	9,391
Common stock available for future awards		297,227
2012 Equity and Incentive Compensation Plan [Member] \| Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock granted			13,322
2012 Equity and Incentive Compensation Plan [Member] \| Share Based Grants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense \| $	$ 605,000		$ 676,000	$ 726,000
2012 Equity and Incentive Compensation Plan [Member] \| Long-Term Incentive Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense \| $	$ 2,341,000		$ 1,359,000	$ 976,000
Non-Employee Director Restricted Stock Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock outstanding	5,068	4,890	5,761	6,454
Compensation expense \| $	$ 349,000	$ 317,000	$ 351,000
Shares authorized under incentive plan	150,000
Common stock granted	5,269	4,890	5,761
Common stock available for future awards	47,748
Restricted stock award for a number of shares \| $	$ 50,000
Non-Employee Director Restricted Stock Plan [Member] \| Restricted Stock [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in annual restricted stock award \| $	$ 75,000