|**Financial Derivative Instruments (Tables)**                           | 9 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
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|**Derivative Instruments and Hedging Activities Disclosure [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      
|Schedule of Derivative Instruments                                      | The details of the interest rate swap agreements are as follows:September 30, 2018December 31, 2017September 30, 2017Notional AmountEffective DateMaturity DateVariable Index ReceivedFixed Rate PaidFair Value(1)Fair Value(1)Fair Value(1)$30,000,000June 28, 2016June 28, 20211-Month  USD LIBOR0.940%$1,552,000$1,154,000$934,00020,000,000June 27, 2016June 27, 20211-Month  USD LIBOR0.893%1,059,000801,000658,00025,000,000June 5, 2018December 5, 20191-Month  USD LIBOR2.466%59,000——25,000,000June 5, 2018June 5, 20201-Month  USD LIBOR2.547%94,000——25,000,000June 5, 2018December 5, 20201-Month  USD LIBOR2.603%124,000——$125,000,000$2,888,000$1,955,000$1,592,000(1) Presented within other assets in the consolidated balance sheet.
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|Notional Amount                                                         | Effective Date                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|$                                                                       | 30,000,000                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
|20,000,000                                                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      
|25,000,000                                                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      
|25,000,000                                                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      
|25,000,000                                                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      
|$                                                                       | 125,000,000                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          

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duration X- DefinitionTabular disclosure of pertinent information about a derivative or group of derivatives on a disaggregated basis, such as for individual instruments, or small groups of similar instruments. May include a combination of the type of instrument, risks being hedged, notional amount, hedge designation, related hedged item, inception date, maturity date, or other relevant item.
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