| **Acquisitions and Divestitures - Narrative (Details) $ / shares in Units, $ in Thousands, shares in Millions** | Dec. 31, 2015 USD ($) bank shares | Apr. 17, 2015 USD ($) bank $ / shares |
|-----------------------------------------------------------------------------------------------------------------|-----------------------------------|---------------------------------------|
| Ameriana                                                                                                        |                              |                                  |
| **Business Acquisition [Line Items]**                                                                           |                              |                                  |
| Percentage of interest acquired                                                                                 | 100.00%                           |                                  |
| Number of banking centers acquired | bank                                                                       | 13                                |                                  |
| Stock issued as a part of acquisition (in shares) | shares                                                      | 2.8                               |                                  |
| Common stock issued, value                                                                                      | $ 70,400                          |                                  |
| Core deposit intangible                                                                                         | $ 5,342                           |                                  |
| Acquired intangible asset, expected useful life                                                                 | 10 years                          |                                  |
| Purchase price                                                                                                  | $ 70,402                          |                                  |
| Ameriana | Common Stock                                                                                         |                              |                                  |
| **Business Acquisition [Line Items]**                                                                           |                              |                                  |
| Number of shares of common stock                                                                                | 0.9037                            |                                  |
| C Financial                                                                                                     |                              |                                  |
| **Business Acquisition [Line Items]**                                                                           |                              |                                  |
| Percentage of interest acquired                                                                                 |                              | 100.00%                               |
| Number of banking centers acquired | bank                                                                       |                              | 6                                     |
| Core deposit intangible                                                                                         |                              | $ 981                                 |
| Acquired intangible asset, expected useful life                                                                 |                              | 10 years                              |
| Purchase price                                                                                                  |                              | $ 14,500                              |
| Cash received by shareholders for each share of common stock held (usd per share) | $ / shares                  |                              | $ 6.738                               |

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Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.
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| - Definition
Percentage of voting equity interests acquired at the acquisition date in the business combination.
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| - Definition
The amount of identifiable intangible assets recognized as of the acquisition date.
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Amount recognized for assets, including goodwill, in excess of (less than) the aggregate liabilities assumed.
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The number of businesses acquired by the entity during the period.
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| - Definition
Number of shares of stock issued during the period pursuant to acquisitions.
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Value of stock issued pursuant to acquisitions during the period.
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