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Fair Values of Assets and Liabilities - Quantitative Inputs and Assumptions Used in Level 3 Fair Value Measurements (Detail) - USD ($) | 6 Months Ended |
--- | --- | ---
Jun. 30, 2020 | Dec. 31, 2019
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
Other Investments | $ 12,272,000 | $ 16,761,000
Assets | 1,013,263,000 | 962,731,000
Impaired Loans [Member] | Reserve Study [Member] |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
Assets | $ 758,000 | 884,000
Impaired Loans [Member] | Reserve Study [Member] | Discount rates [Member] | Weighted average [Member] |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
Discount Rate | 10.00% |
Impaired Loans [Member] | Reserve Study [Member] | Gas per MCF [Member] | Minimum [Member] |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
Fair Value Inputs Monetary | $ 1.46 |
Impaired Loans [Member] | Reserve Study [Member] | Gas per MCF [Member] | Maximum [Member] |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
Fair Value Inputs Monetary | 1.48 |
Impaired Loans [Member] | Reserve Study [Member] | Oil per BBL/d [Member] | Minimum [Member] |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
Fair Value Inputs Monetary | 36.00 |
Impaired Loans [Member] | Reserve Study [Member] | Oil per BBL/d [Member] | Maximum [Member] |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
Fair Value Inputs Monetary | 36.00 |
Impaired Loans [Member] | Discounted Cash Flow [Member] |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
Assets | 0 | 2,239,000
Limited Partnership Investment [Member] |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
Assets | 6,406,000 | 5,795,000
Level 3 [Member] |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
Other Investments | 1,670,000 | 1,670,000
Assets | $ 8,076,000 | $ 7,465,000

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- Definition Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
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