|**Transfers Accounted for as Secured Borrowings (Tables)**                                       | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                
|------------------------------------------------------------------------------------------------ | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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|**Banking and Thrift [Abstract]**                                                                |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                
|Schedule of Collateral Pledged for all Repurchase Agreements Accounted for as Secured Borrowings | The collateral pledged for all repurchase agreements that are accounted for as secured borrowings as ofDecember 31, 2017and2016were:December 31, 2017Remaining Contractual Maturity of the AgreementsOvernight and ContinuousUp to 30 Days30-90 DaysGreater Than 90 DaysTotalU.S. Government-sponsored mortgage-backed securities$126,1871,3401,500$7,596$136,623December 31, 2016Remaining Contractual Maturity of the AgreementsOvernight and ContinuousUp to 30 Days30-90 DaysGreater Than 90 DaysTotalU.S. Government-sponsored mortgage-backed securities$129,6171,33710,253$5,273$146,480
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|                                                                                                 | December 31, 2017                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              
|                                                                                                 | Remaining Contractual Maturity of the Agreements                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               
|                                                                                                 | Overnight and Continuous                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|U.S. Government-sponsored mortgage-backed securities                                             | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              
|                                                                                                
|                                                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                
|                                                                                                 | December 31, 2016                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              
|                                                                                                 | Remaining Contractual Maturity of the Agreements                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               
|                                                                                                 | Overnight and Continuous                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|U.S. Government-sponsored mortgage-backed securities                                             | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              

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+ ReferencesReference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(m)(1)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690
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