Disclosures of Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Available-for-sale: [Abstract]
Total available-for-sale securities	$ 578,579	$ 619,848
Impaired Loans Receivable [Abstract]
Carrying amount of loans with a specific allowance		8,370
Fair value of loans with a specific allowance		6,938
Specific Allowance		1,432
Fair Value, Measurements, Recurring [Member]
Available-for-sale: [Abstract]
Total available-for-sale securities	578,579	619,848
Fair Value, Measurements, Recurring [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Available-for-sale: [Abstract]
Total available-for-sale securities	172	144
Fair Value, Measurements, Recurring [Member] \| Significant Other Observable Inputs (Level 2)
Available-for-sale: [Abstract]
Total available-for-sale securities	575,859	618,052
Fair Value, Measurements, Recurring [Member] \| Significant Unobservable Inputs (Level 3)
Available-for-sale: [Abstract]
Total available-for-sale securities	2,548	1,652
Fair Value, Measurements, Nonrecurring [Member]
Impaired Loans Receivable [Abstract]
Carrying amount of loans with a specific allowance	3,665
Fair value of loans with a specific allowance	3,053
Specific Allowance	612
U.S. Treasury securities and obligations of U.S. government corporations & agencies
Available-for-sale: [Abstract]
Total available-for-sale securities	113,770	136,324
U.S. Treasury securities and obligations of U.S. government corporations & agencies \| Fair Value, Measurements, Recurring [Member]
Available-for-sale: [Abstract]
Total available-for-sale securities	113,770	136,324
U.S. Treasury securities and obligations of U.S. government corporations & agencies \| Fair Value, Measurements, Recurring [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Available-for-sale: [Abstract]
Total available-for-sale securities	0	0
U.S. Treasury securities and obligations of U.S. government corporations & agencies \| Fair Value, Measurements, Recurring [Member] \| Significant Other Observable Inputs (Level 2)
Available-for-sale: [Abstract]
Total available-for-sale securities	113,770	136,324
U.S. Treasury securities and obligations of U.S. government corporations & agencies \| Fair Value, Measurements, Recurring [Member] \| Significant Unobservable Inputs (Level 3)
Available-for-sale: [Abstract]
Total available-for-sale securities	0	0
Obligations of states and political subdivisions
Available-for-sale: [Abstract]
Total available-for-sale securities	166,266	162,705
Obligations of states and political subdivisions \| Fair Value, Measurements, Recurring [Member]
Available-for-sale: [Abstract]
Total available-for-sale securities	166,266	162,705
Obligations of states and political subdivisions \| Fair Value, Measurements, Recurring [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Available-for-sale: [Abstract]
Total available-for-sale securities	0	0
Obligations of states and political subdivisions \| Fair Value, Measurements, Recurring [Member] \| Significant Other Observable Inputs (Level 2)
Available-for-sale: [Abstract]
Total available-for-sale securities	166,266	162,705
Obligations of states and political subdivisions \| Fair Value, Measurements, Recurring [Member] \| Significant Unobservable Inputs (Level 3)
Available-for-sale: [Abstract]
Total available-for-sale securities	0	0
Mortgage-backed securities
Available-for-sale: [Abstract]
Total available-for-sale securities	293,811	314,991
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	1,652
Transfers into Level 3	0
Transfers out of Level 3	0
Total gains or losses [Abstract]
Included in net income	0
Included in other comprehensive income (loss)	1,053
Purchases, issuances, sales and settlements [Abstract]
Purchases	0
Issuances	0
Sales	0
Settlements	(157)
Ending balance	2,548
Total gains or losses for the period included in net income attributable to the change in unrealized gains or losses related to assets and liabilities still held at the reporting date	0
Mortgage-backed securities \| Fair Value, Measurements, Recurring [Member]
Available-for-sale: [Abstract]
Total available-for-sale securities	293,811	314,991
Mortgage-backed securities \| Fair Value, Measurements, Recurring [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Available-for-sale: [Abstract]
Total available-for-sale securities	0	0
Mortgage-backed securities \| Fair Value, Measurements, Recurring [Member] \| Significant Other Observable Inputs (Level 2)
Available-for-sale: [Abstract]
Total available-for-sale securities	293,811	314,991
Mortgage-backed securities \| Fair Value, Measurements, Recurring [Member] \| Significant Unobservable Inputs (Level 3)
Available-for-sale: [Abstract]
Total available-for-sale securities	0	0
Trust preferred securities
Available-for-sale: [Abstract]
Total available-for-sale securities	2,548	1,652
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	1,906
Transfers into Level 3	0
Transfers out of Level 3	0
Total gains or losses [Abstract]
Included in net income	0
Included in other comprehensive income (loss)	(174)
Purchases, issuances, sales and settlements [Abstract]
Purchases	0
Issuances	0
Sales	0
Settlements	(80)
Ending balance	1,652
Total gains or losses for the period included in net income attributable to the change in unrealized gains or losses related to assets and liabilities still held at the reporting date	0
Trust preferred securities \| Fair Value, Measurements, Recurring [Member]
Available-for-sale: [Abstract]
Total available-for-sale securities	2,548	1,652
Trust preferred securities \| Fair Value, Measurements, Recurring [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Available-for-sale: [Abstract]
Total available-for-sale securities	0	0
Trust preferred securities \| Fair Value, Measurements, Recurring [Member] \| Significant Other Observable Inputs (Level 2)
Available-for-sale: [Abstract]
Total available-for-sale securities	0	0
Trust preferred securities \| Fair Value, Measurements, Recurring [Member] \| Significant Unobservable Inputs (Level 3)
Available-for-sale: [Abstract]
Total available-for-sale securities	2,548	1,652
Other securities
Available-for-sale: [Abstract]
Total available-for-sale securities	2,184	4,176
Other securities \| Fair Value, Measurements, Recurring [Member]
Available-for-sale: [Abstract]
Total available-for-sale securities	2,184	4,176
Other securities \| Fair Value, Measurements, Recurring [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Available-for-sale: [Abstract]
Total available-for-sale securities	172	144
Other securities \| Fair Value, Measurements, Recurring [Member] \| Significant Other Observable Inputs (Level 2)
Available-for-sale: [Abstract]
Total available-for-sale securities	2,012	4,032
Other securities \| Fair Value, Measurements, Recurring [Member] \| Significant Unobservable Inputs (Level 3)
Available-for-sale: [Abstract]
Total available-for-sale securities	$ 0	$ 0

Amount of allowance for credit losses related to recorded investment measured at fair value on a nonrecurring basis.

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Amount of investment in impaired financing receivables, for which there is a related allowance for credit losses, measured at fair value on a nonrecurring basis.

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Unpaid principal balance of impaired financing receivables, for which there is a related allowance for credit losses, measured at fair value on a nonrecurring basis.

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Amount of investments in debt securities classified as available-for-sale, expected to be converted to cash, sold or exchanged within one year or the normal operating cycle, if longer.

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Amount of gain (loss) recognized in the income statement for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of gain (loss) recognized in other comprehensive income (loss) for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of issuances of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of transfers of financial instrument classified as an asset out of level 3 of the fair value hierarchy.

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount after tax of reclassification adjustment from accumulated other comprehensive income for unrealized loss realized upon the write-down of available-for-sale securities.

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