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Fair Value of Assets and Liabilities - Recorded on a Recurring Basis (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2017 USD ($) security	Dec. 31, 2016 USD ($) security
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 258,092	$ 372,580
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of securities | security	0	0
Debentures of government- sponsored agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 30,382	$ 35,403
Privately-issued collateralized mortgage obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	128	419
Obligations of state and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	75,181	77,701
Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	5,031	5,016
U.S. government agency obligation collateralized by loans guaranteed by SBA program | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Increase in unrealized gain (loss) due to transfers to Level 3	$ 2
U.S. government agency obligation collateralized by loans guaranteed by SBA program | Significant Unobservable Inputs (Level 3) | Available-for-sale Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of securities | security	1
Assets and liabilities at fair value measured on a recurring basis | Carrying Value | Interest rate contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial assets (interest rate contracts)	$ 38	55
Derivative financial liabilities (interest rate contracts)	909	933
Assets and liabilities at fair value measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Interest rate contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial assets (interest rate contracts)	0	0
Derivative financial liabilities (interest rate contracts)	0	0
Assets and liabilities at fair value measured on a recurring basis | Significant Other Observable Inputs (Level 2) | Interest rate contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial assets (interest rate contracts)	38	55
Derivative financial liabilities (interest rate contracts)	909	933
Assets and liabilities at fair value measured on a recurring basis | Significant Unobservable Inputs (Level 3) | Interest rate contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial assets (interest rate contracts)	0	0
Derivative financial liabilities (interest rate contracts)	0	0
Assets and liabilities at fair value measured on a recurring basis | Mortgage-backed securities and collateralized mortgage obligations issued by U.S. government agencies | Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	147,370	254,041
Assets and liabilities at fair value measured on a recurring basis | Mortgage-backed securities and collateralized mortgage obligations issued by U.S. government agencies | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Assets and liabilities at fair value measured on a recurring basis | Mortgage-backed securities and collateralized mortgage obligations issued by U.S. government agencies | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	146,818	253,434
Assets and liabilities at fair value measured on a recurring basis | Mortgage-backed securities and collateralized mortgage obligations issued by U.S. government agencies | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	552	607
Assets and liabilities at fair value measured on a recurring basis | Debentures of government- sponsored agencies | Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	30,382	35,403
Assets and liabilities at fair value measured on a recurring basis | Debentures of government- sponsored agencies | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Assets and liabilities at fair value measured on a recurring basis | Debentures of government- sponsored agencies | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	30,382	35,403
Assets and liabilities at fair value measured on a recurring basis | Debentures of government- sponsored agencies | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Assets and liabilities at fair value measured on a recurring basis | Privately-issued collateralized mortgage obligations | Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	128	419
Assets and liabilities at fair value measured on a recurring basis | Privately-issued collateralized mortgage obligations | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Assets and liabilities at fair value measured on a recurring basis | Privately-issued collateralized mortgage obligations | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	128	419
Assets and liabilities at fair value measured on a recurring basis | Privately-issued collateralized mortgage obligations | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Assets and liabilities at fair value measured on a recurring basis | Obligations of state and political subdivisions | Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	75,181	77,701
Assets and liabilities at fair value measured on a recurring basis | Obligations of state and political subdivisions | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Assets and liabilities at fair value measured on a recurring basis | Obligations of state and political subdivisions | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	75,181	77,701
Assets and liabilities at fair value measured on a recurring basis | Obligations of state and political subdivisions | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Assets and liabilities at fair value measured on a recurring basis | Corporate bonds | Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	5,031	5,016
Assets and liabilities at fair value measured on a recurring basis | Corporate bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Assets and liabilities at fair value measured on a recurring basis | Corporate bonds | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	5,031	5,016
Assets and liabilities at fair value measured on a recurring basis | Corporate bonds | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 0	$ 0

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