| **Investment Securities - Narrative (Details)**                                            | Sep. 30, 2017 USD ($) security | Dec. 31, 2016 USD ($) |
|--------------------------------------------------------------------------------------------|--------------------------------|-----------------------|
| **Investments, Debt and Equity Securities [Abstract]**                                     |                           |                  |
| Carrying value of securities pledged as collateral                                         | $ 511,192,000                  | $ 572,896,000         |
| Book value of securities sold under agreements to repurchase                               | 141,329,000                    | 145,936,000           |
| **Schedule of Available for sale Securities and Held to maturity Securities [Line Items]** |                           |                  |
| Available-for-sale unrealized losses                                                       | 3,963,000                      | 9,674,000             |
| Held-to-maturity unrealized losses                                                         | 1,698,000                      | 3,802,000             |
| State and municipal                                                                        |                           |                  |
| **Schedule of Available for sale Securities and Held to maturity Securities [Line Items]** |                           |                  |
| Available-for-sale unrealized losses                                                       | $ 2,006,000                    | 5,564,000             |
| Available-for-sale, number of securities in unrealized loss positions | security           | 83                             |                  |
| Held-to-maturity unrealized losses                                                         | $ 575,000                      | 1,796,000             |
| Held-to-maturity, number of securities in unrealized loss positions | security             | 31                             |                  |
| U.S. Government-sponsored agency securities                                                |                           |                  |
| **Schedule of Available for sale Securities and Held to maturity Securities [Line Items]** |                           |                  |
| Available-for-sale unrealized losses                                                       | $ 0                            |                  |
| Available-for-sale, number of securities in unrealized loss positions | security           | 0                              |                  |
| Held-to-maturity unrealized losses                                                         | $ 311,000                      | 479,000               |
| Held-to-maturity, number of securities in unrealized loss positions | security             | 4                              |                  |
| U.S. Government-sponsored mortgage-backed securities                                       |                           |                  |
| **Schedule of Available for sale Securities and Held to maturity Securities [Line Items]** |                           |                  |
| Available-for-sale unrealized losses                                                       | $ 1,957,000                    | 3,071,000             |
| Available-for-sale, number of securities in unrealized loss positions | security           | 39                             |                  |
| Held-to-maturity unrealized losses                                                         | $ 812,000                      | $ 1,527,000           |
| Held-to-maturity, number of securities in unrealized loss positions | security             | 23                             |                  |

| X                                                                                                                                                                                                                                                                                                                                                |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
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| X                                                                                                                                                                                                                                                   |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Securities Pledged as Collateral
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Carrying amount of assets sold under agreements to repurchase when the carrying amount (or market value, if higher than the carrying amount) of securities or other assets sold under repurchase agreements exceeds 10 percent of total assets.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.
+ References
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|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Number of investment positions in available-for-sale investments in a continuous unrealized loss position for which an other-than-temporary impairment (OTTI) has not been recognized in the income statement.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of accumulated unrealized loss on investments in debt securities classified as held-to-maturity.
+ References
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|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Disclosure regarding factors used to determine that the impairment of securities categorized as held-to-maturity where cost exceeds fair value is not an other than temporary impairment (OTTI). This item contains disclosure of the number of investment positions in the held-to-maturity investments determined to be temporarily impaired.
+ References
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| - References
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