Securities (Tables)
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9 Months Ended | 
Sep. 30, 2018  | 
| Investments, Debt and Equity Securities [Abstract] | 
 
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| Available-for-sale Securities [Table Text Block] | 
The estimated fair value of available-for-sale securities and the related gross unrealized gains and losses recognized in accumulated other comprehensive income were as follows:  
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U.S. government sponsored entities  | 
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Collateralized mortgage obligations and residential mortgage-backed securities  | 
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Collateralized debt obligations  | 
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Total securities available-for-sale  | 
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U.S. government sponsored entities  | 
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Collateralized mortgage obligations and residential mortgage-backed securities  | 
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Collateralized debt obligations  | 
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Total securities available-for-sale  | 
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| Schedule of Contractual Maturities of Available-for-sale Debt Securities [Table Text Block] | 
The estimated fair value of available-for-sale debt securities at September 30, 2018, by contractual maturity, were as follows. Securities not due at a single maturity date, primarily collateralized mortgage obligations and residential mortgage-backed securities, are shown separately.  
  
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Due from one to five years  | 
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Due from five to ten years  | 
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Collateralized mortgage obligations and residential mortgage-backed securities  | 
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| Schedule of Realized Gain (Loss) [Table Text Block] | 
Sales of available-for-sale securities were as follows for the nine months ended:  
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| Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] | 
Accumulated other comprehensive income/(loss) balances, net of tax, related to available-for-sale securities, were as follows:  
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Ending balance, December 31, 2017  | 
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Ending balance, September 30, 2018  | 
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| Unrealized Gain (Loss) on Investments [Table Text Block] | 
Securities with gross unrealized losses at September 30, 2018 and December 31, 2017 not recognized in income are as follows:  
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U.S. government sponsored entities  | 
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Collateralized mortgage obligations and residential mortgage-backed securities  | 
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Collateralized debt obligations  | 
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Total temporarily impaired  | 
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U.S. government sponsored entities  | 
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Collateralized mortgage obligations and residential mortgage-backed securities  | 
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Collateralized debt obligations  | 
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Total temporarily impaired  | 
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