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Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) | Mar. 31, 2019 | Dec. 31, 2018
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Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Transfers between Level 1 to Level 2 | $ 0 | $ 0
ASSETS |  |
Debt securities available-for-sale | 675,922,000 | 680,056,000
Marketable equity securities | 4,498,000 | 4,816,000
U.S. Treasury securities |  |
ASSETS |  |
Debt securities available-for-sale | 9,837,000 | 9,736,000
Obligations of U.S. government corporations and agencies |  |
ASSETS |  |
Debt securities available-for-sale | 129,369,000 | 128,261,000
Collateralized mortgage obligations of U.S. government corporations and agencies |  |
ASSETS |  |
Debt securities available-for-sale | 154,159,000 | 148,659,000
Residential mortgage-backed securities of U.S. government corporations and agencies |  |
ASSETS |  |
Debt securities available-for-sale | 22,514,000 | 24,350,000
Commercial mortgage-backed securities of U.S. government corporations and agencies |  |
ASSETS |  |
Debt securities available-for-sale | 237,554,000 | 246,784,000
Obligations of states and political subdivisions |  |
ASSETS |  |
Debt securities available-for-sale | 122,489,000 | 122,266,000
Fair Value Measurements, Recurring |  |
ASSETS |  |
Debt securities available-for-sale | 675,922,000 | 680,056,000
Marketable equity securities | 4,498,000 | 4,816,000
Total securities | 680,420,000 | 684,872,000
Securities held in a deferred compensation plan | 5,343,000 | 4,725,000
Total Assets | 696,835,000 | 695,407,000
LIABILITIES |  |
Total Liabilities | 10,602,000 | 5,340,000
Fair Value Measurements, Recurring | U.S. Treasury securities |  |
ASSETS |  |
Debt securities available-for-sale | 9,837,000 | 9,736,000
Fair Value Measurements, Recurring | Obligations of U.S. government corporations and agencies |  |
ASSETS |  |
Debt securities available-for-sale | 129,369,000 | 128,261,000
Fair Value Measurements, Recurring | Collateralized mortgage obligations of U.S. government corporations and agencies |  |
ASSETS |  |
Debt securities available-for-sale | 154,159,000 | 148,659,000
Fair Value Measurements, Recurring | Residential mortgage-backed securities of U.S. government corporations and agencies |  |
ASSETS |  |
Debt securities available-for-sale | 22,514,000 | 24,350,000
Fair Value Measurements, Recurring | Commercial mortgage-backed securities of U.S. government corporations and agencies |  |
ASSETS |  |
Debt securities available-for-sale | 237,554,000 | 246,784,000
Fair Value Measurements, Recurring | Obligations of states and political subdivisions |  |
ASSETS |  |
Debt securities available-for-sale | 122,489,000 | 122,266,000
Fair Value Measurements, Recurring | Interest rate swaps |  |
ASSETS |  |
Derivative financial assets | 10,645,000 | 5,504,000
LIABILITIES |  |
Interest rate swaps | 10,602,000 | 5,340,000
Fair Value Measurements, Recurring | Interest rate lock commitments |  |
ASSETS |  |
Derivative financial assets | 339,000 | 251,000
Fair Value Measurements, Recurring | Forward sale contracts—mortgage loans |  |
ASSETS |  |
Derivative financial assets | 88,000 | 55,000
Fair Value Measurements, Recurring | Level 1 |  |
ASSETS |  |
Debt securities available-for-sale | 0 | 0
Marketable equity securities | 0 | 0
Total securities | 0 | 0
Securities held in a deferred compensation plan | 5,343,000 | 4,725,000
Total Assets | 5,343,000 | 4,725,000
LIABILITIES |  |
Total Liabilities | 0 | 0
Fair Value Measurements, Recurring | Level 1 | U.S. Treasury securities |  |
ASSETS |  |
Debt securities available-for-sale | 0 | 0
Fair Value Measurements, Recurring | Level 1 | Obligations of U.S. government corporations and agencies |  |
ASSETS |  |
Debt securities available-for-sale | 0 | 0
Fair Value Measurements, Recurring | Level 1 | Collateralized mortgage obligations of U.S. government corporations and agencies |  |
ASSETS |  |
Debt securities available-for-sale | 0 | 0
Fair Value Measurements, Recurring | Level 1 | Residential mortgage-backed securities of U.S. government corporations and agencies |  |
ASSETS |  |
Debt securities available-for-sale | 0 | 0
Fair Value Measurements, Recurring | Level 1 | Commercial mortgage-backed securities of U.S. government corporations and agencies |  |
ASSETS |  |
Debt securities available-for-sale | 0 | 0
Fair Value Measurements, Recurring | Level 1 | Obligations of states and political subdivisions |  |
ASSETS |  |
Debt securities available-for-sale | 0 | 0
Fair Value Measurements, Recurring | Level 1 | Interest rate swaps |  |
ASSETS |  |
Derivative financial assets | 0 | 0
LIABILITIES |  |
Interest rate swaps | 0 | 0
Fair Value Measurements, Recurring | Level 1 | Interest rate lock commitments |  |
ASSETS |  |
Derivative financial assets | 0 | 0
Fair Value Measurements, Recurring | Level 1 | Forward sale contracts—mortgage loans |  |
ASSETS |  |
Derivative financial assets | 0 | 0
Fair Value Measurements, Recurring | Level 2 |  |
ASSETS |  |
Debt securities available-for-sale | 675,922,000 | 680,056,000
Marketable equity securities | 4,498,000 | 4,816,000
Total securities | 680,420,000 | 684,872,000
Securities held in a deferred compensation plan | 0 | 0
Total Assets | 691,492,000 | 690,682,000
LIABILITIES |  |
Total Liabilities | 10,602,000 | 5,340,000
Fair Value Measurements, Recurring | Level 2 | U.S. Treasury securities |  |
ASSETS |  |
Debt securities available-for-sale | 9,837,000 | 9,736,000
Fair Value Measurements, Recurring | Level 2 | Obligations of U.S. government corporations and agencies |  |
ASSETS |  |
Debt securities available-for-sale | 129,369,000 | 128,261,000
Fair Value Measurements, Recurring | Level 2 | Collateralized mortgage obligations of U.S. government corporations and agencies |  |
ASSETS |  |
Debt securities available-for-sale | 154,159,000 | 148,659,000
Fair Value Measurements, Recurring | Level 2 | Residential mortgage-backed securities of U.S. government corporations and agencies |  |
ASSETS |  |
Debt securities available-for-sale | 22,514,000 | 24,350,000
Fair Value Measurements, Recurring | Level 2 | Commercial mortgage-backed securities of U.S. government corporations and agencies |  |
ASSETS |  |
Debt securities available-for-sale | 237,554,000 | 246,784,000
Fair Value Measurements, Recurring | Level 2 | Obligations of states and political subdivisions |  |
ASSETS |  |
Debt securities available-for-sale | 122,489,000 | 122,266,000
Fair Value Measurements, Recurring | Level 2 | Interest rate swaps |  |
ASSETS |  |
Derivative financial assets | 10,645,000 | 5,504,000
LIABILITIES |  |
Interest rate swaps | 10,602,000 | 5,340,000
Fair Value Measurements, Recurring | Level 2 | Interest rate lock commitments |  |
ASSETS |  |
Derivative financial assets |  | 251,000
Fair Value Measurements, Recurring | Level 2 | Forward sale contracts—mortgage loans |  |
ASSETS |  |
Derivative financial assets |  | 55,000
Fair Value Measurements, Recurring | Level 3 |  |
ASSETS |  |
Debt securities available-for-sale | 0 | 0
Marketable equity securities | 0 | 0
Total securities | 0 | 0
Securities held in a deferred compensation plan | 0 | 0
Total Assets | 0 | 0
LIABILITIES |  |
Total Liabilities | 0 | 0
Fair Value Measurements, Recurring | Level 3 | U.S. Treasury securities |  |
ASSETS |  |
Debt securities available-for-sale | 0 | 0
Fair Value Measurements, Recurring | Level 3 | Obligations of U.S. government corporations and agencies |  |
ASSETS |  |
Debt securities available-for-sale | 0 | 0
Fair Value Measurements, Recurring | Level 3 | Collateralized mortgage obligations of U.S. government corporations and agencies |  |
ASSETS |  |
Debt securities available-for-sale | 0 | 0
Fair Value Measurements, Recurring | Level 3 | Residential mortgage-backed securities of U.S. government corporations and agencies |  |
ASSETS |  |
Debt securities available-for-sale | 0 | 0
Fair Value Measurements, Recurring | Level 3 | Commercial mortgage-backed securities of U.S. government corporations and agencies |  |
ASSETS |  |
Debt securities available-for-sale | 0 | 0
Fair Value Measurements, Recurring | Level 3 | Obligations of states and political subdivisions |  |
ASSETS |  |
Debt securities available-for-sale | 0 | 0
Fair Value Measurements, Recurring | Level 3 | Interest rate swaps |  |
ASSETS |  |
Derivative financial assets | 0 | 0
LIABILITIES |  |
Interest rate swaps | 0 | 0
Fair Value Measurements, Recurring | Level 3 | Interest rate lock commitments |  |
ASSETS |  |
Derivative financial assets | 0 | 0
Fair Value Measurements, Recurring | Level 3 | Forward sale contracts—mortgage loans |  |
ASSETS |  |
Derivative financial assets | $ 0 | $ 0

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