Share-Based Compensation - Additional Information (Detail) - USD ($)	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Compensation expense in stock compensation plans	$ 181,595	$ 219,051	$ 778,763	$ 863,592
Income tax benefit of stock compensation plans	38,135	46,001	163,540	181,354
Unrecognized compensation expense related to nonvested share-based compensation granted under the plan	852,888		$ 852,888
Weighted average period of unrecognized compensation expense			1 year 4 months 24 days
Cash from option exercises	764,956	8,100,000	$ 12,200,000	11,200,000
Tax benefit for tax deductions related to option exercises	$ 16,655	$ 163,245	$ 437,790	$ 232,123

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

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Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of tax benefit for recognition of expense of award under share-based payment arrangement.

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Amount of tax benefit from exercise of option under share-based payment arrangement.

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