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Derivative Financial Instruments (Narrative) (Details) $ in Millions | 1 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Mar. 31, 2016 USD ($) contract | Dec. 31, 2020 USD ($) | Dec. 31, 2019 USD ($)
Derivative [Line Items] |  |  |
Decrease in fair value of derivatives |  | $ 1.2 |
Cash flow hedge ineffectiveness |  | $ 0.3 |
Cash flow hedge ineffectiveness |  | Interest rate swap agreements are entered into with counterparties that meet established credit standards and the Corporation believes that the credit risk inherent in these contracts is not significant at December 31, 2020. |
Interest Rate Swap Agreements [Member] |  |  |
Derivative [Line Items] |  |  |
Interest rate swap notional amount | $ 30.0 |  |
Number of interest rate swap contracts | contract | 4 |  |
Interest rate swap fair value |  | $ (1.3) | $ (0.1)
Swap Contract 3 Year 5 Million [Member] |  |  |
Derivative [Line Items] |  |  |
Interest rate swap notional amount | $ 5.0 |  |
Derivative, maturity date | Jun. 17, 2019 |  |
Derivative, term of contract | 3 years |  |
Swap Contract 5 Year $5 Million [Member] |  |  |
Derivative [Line Items] |  |  |
Interest rate swap notional amount | $ 5.0 |  |
Derivative, maturity date | Mar. 17, 2021 |  |
Derivative, term of contract | 5 years |  |
Swap Contract- 7 year $5 Million [Member] |  |  |
Derivative [Line Items] |  |  |
Interest rate swap notional amount | $ 5.0 |  |
Derivative, maturity date | Mar. 17, 2023 |  |
Derivative, term of contract | 7 years |  |
Swap Contract 10 Year $15 Million [Member] |  |  |
Derivative [Line Items] |  |  |
Interest rate swap notional amount | $ 15.0 |  |
Derivative, maturity date | Mar. 17, 2026 |  |
Derivative, term of contract | 10 years |  |

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- Definition A disclosure of an assertion that the amount of cash flow hedge ineffectiveness is immaterial. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624171-113959 + Details
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- Definition Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226000-175313 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 20 -Section 50 -Paragraph 4D -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=121570589&loc=SL51823488-111719 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -Subparagraph (a),(c) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624163-113959 + Details
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- Definition Amount of decrease in the fair value of derivatives recognized in the income statement. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5618551-113959 + Details
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- Definition Period the derivative contract is outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
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- Definition The net gain (loss) recognized in earnings during the reporting period representing the amount of the cash flow hedges' ineffectiveness. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624171-113959 + Details
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