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Income Taxes - Additional Information (Detail) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Operating Loss Carryforwards [Line Items] |  |  |
Effective tax rate computed at the statutory federal rate | 21.00% | 21.00% | 35.00%
Additional tax expense related to new corporate tax rate reform |  |  | $ 4,752,547
Reclassification of an alternative minimum tax credit carry forward |  |  | $ 8,500,000
Net operating loss carryback period | 2 years |  |
Operating loss carryforwards expiration period | 2038 |  |
Other deferred tax assets, net | $ 26,100,000 | $ 32,400,000 |
Parent Company [Member] |  |  |
Operating Loss Carryforwards [Line Items] |  |  |
Valuation allowance related to the portion of operating loss carryforwards | 7,500,000 | $ 8,100,000 |
Earliest Tax Year [Member] |  |  |
Operating Loss Carryforwards [Line Items] |  |  |
Tax years open for examination |  | 2016 |
Latest Tax Year [Member] |  |  |
Operating Loss Carryforwards [Line Items] |  |  |
Tax years open for examination |  | 2019 |
Le Mars [Member] |  |  |
Operating Loss Carryforwards [Line Items] |  |  |
Valuation allowance related to the portion of operating loss carryforwards | 18,033 | $ 18,033 |
Operating loss carryforwards | $ 956,865 |  |
Operating loss carryforwards expiration period | 2020 |  |
Operating loss carryforwards annual limitations in amount on use | $ 376,000 |  |

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