| **Core Deposit and Other Intangibles**                   | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
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| **Goodwill and Intangible Assets Disclosure [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
| Core Deposit and Other Intangibles                       | CORE DEPOSIT AND OTHER INTANGIBLESCore deposit and other intangibles are recorded on the acquisition date of an entity. During the measurement period, the Corporation may record subsequent adjustments to core deposit and other intangibles for provisional amounts recorded at the acquisition date. The Ameriana acquisition on December 31, 2015 resulted in a core deposit intangible of  $5,342,000, of which, $2,142,000 was recorded as a measurement period adjustment in the first quarter of 2016. The C Financial acquisition on April 17, 2015 resulted in a core deposit intangible of $981,000.  On June 12, 2015, the sale of FMIG resulted in an other intangible reduction of $742,000. Details regarding the acquisitions and sale are discussed in Note 2. ACQUISITIONS AND DIVESTITURES, in the Notes to Consolidated Financial Statements included as Item 8 of this Annual Report on Form 10-K. The carrying basis and accumulated amortization of recognized core deposit and other intangibles are noted below.   20162015Gross carrying amount$61,798$58,360Core deposit intangible and other intangibles acquired4,181Measurement period adjustment2,142Accumulated amortization(49,074)(45,164)Core deposit intangible and other intangibles reduction(742)Core Deposit and Other Intangibles$14,866$16,635 Amortization expense for the years ended December 31, 2016, 2015 and 2014, was $3,910,000, $2,835,000 and $2,445,000, respectively. Estimated future amortization expense is summarized as follows: Amortization Expense2017$3,61420182,29920191,91420201,73320211,611After 20213,695 $14,866 |

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| - Definition
The entire disclosure for all or part of the information related to intangible assets.
+ References
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