|**Goodwill**                                             | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        
|-------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|
|**Goodwill and Intangible Assets Disclosure [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        
|Goodwill                                                 | GOODWILLThe Ameriana acquisition on December 31, 2015 resulted in$38,624,000of goodwill, of which,$871,000was recorded during the first quarter of 2016 as a measurement period adjustment.  The C Financial acquisition on April 17, 2015 resulted in goodwill of$11,126,000.  On June 12, 2015, the sale of FMIG resulted in a goodwill reduction of$8,474,000. 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.Noimpairment loss was recorded in 2016 or 2015.  The Corporation tested goodwill for impairment during 2016 and 2015.  In both valuations, the fair value exceeded the Corporation’s carrying value; therefore, it was concluded goodwill is not impaired. For additional details related to impairment testing, see the “GOODWILL” section of Management’s Discussion and Analysis of Financial Condition and Results of Operations included as Item 7 of this Annual Report on Form 10-K.20162015Balance, January 1$243,129$202,724Goodwill acquired48,879Goodwill reduction(8,474)Measurement period adjustment871Balance, December 31$244,000$243,129
|                                                        
|                                                         |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        
|                                                         | 2016                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   
|Balance, January 1                                       | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      
|Goodwill acquired                                        |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        
|Goodwill reduction                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        
|Measurement period adjustment                            | 871                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
|Balance, December 31                                     | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      

X- ReferencesNo definition available.
+ Details**Name:**
us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract**Namespace Prefix:**
us-gaap_**Data Type:**
xbrli:stringItemType**Balance Type:**
na**Period Type:**
duration X- DefinitionThe entire disclosure for goodwill.
+ ReferencesNo definition available.
+ Details**Name:**
us-gaap_GoodwillDisclosureTextBlock**Namespace Prefix:**
us-gaap_**Data Type:**
nonnum:textBlockItemType**Balance Type:**
na**Period Type:**
duration