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Derivatives And Risk Management (Interest Rate Swap Agreements) (Details) - Interest Rate Swap [Member] $ in Thousands | 3 Months Ended | 12 Months Ended
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Mar. 31, 2019 USD ($) Caontracts | Dec. 31, 2018 USD ($) Caontracts
2019 |  |
Derivatives, Fair Value [Line Items] |  |
Number of Interest Rate Derivatives Held | Caontracts | 6 | 6
Derivative, Notional Amount | $ | $ 70,000 | $ 70,000
Derivative, Maturity Date | Dec. 31, 2019 | Dec. 31, 2019
2020 |  |
Derivatives, Fair Value [Line Items] |  |
Number of Interest Rate Derivatives Held | Caontracts | 6 | 6
Derivative, Notional Amount | $ | $ 60,000 | $ 60,000
Derivative, Maturity Date | Dec. 31, 2020 | Dec. 31, 2020
2021 |  |
Derivatives, Fair Value [Line Items] |  |
Number of Interest Rate Derivatives Held | Caontracts | 2 | 2
Derivative, Notional Amount | $ | $ 25,000 | $ 25,000
Derivative, Maturity Date | Dec. 31, 2021 | Dec. 31, 2021
2022 |  |
Derivatives, Fair Value [Line Items] |  |
Number of Interest Rate Derivatives Held | Caontracts | 8 | 7
Derivative, Notional Amount | $ | $ 90,000 | $ 80,000
Derivative, Maturity Date | Dec. 31, 2022 | Dec. 31, 2022

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- Definition Aggregate notional amount specified by the derivative(s). Expressed as an absolute value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B + Details
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- Definition Date the derivative contract matures, in CCYY-MM-DD format. + References No definition available. + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition Number of interest rate derivative instruments held by the entity at the reporting date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5579245-113959 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5580258-113959 + Details
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