Accounting for Certain Loans Acquired in a Purchase - Carrying Amount of Loans Included in Balance Sheet (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	$ 914,347	$ 961,382
Carrying Amount	870,507	917,589
Allowance	155	153
Carrying Amount Net of Allowance	870,352	917,436
Loans acquired and accounted for under ASC 310-30, outstanding balance	84,500	95,800
Loans acquired and accounted for under ASC 310-30, carrying amount	60,100	69,600
Commercial and industrial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	85,513	85,441
Agricultural production financing and other loans to farmers
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	3,735	3,049
Real estate loans - Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	47,885	40,991
Real estate loans - Commercial and farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	392,476	425,014
Real estate loans - Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	307,326	325,141
Real estate loans - Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	73,364	77,053
Individuals' loans for household and other personal expenditures
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	2,138	2,693
Other commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	1,910	2,000
Ameriana
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	317,927	330,918
Carrying Amount	304,615	319,664
Carrying Amount Net of Allowance	304,615	319,664
Ameriana | Commercial and industrial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	23,363	21,888
Ameriana | Real estate loans - Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	30,414	23,365
Ameriana | Real estate loans - Commercial and farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	131,371	144,514
Ameriana | Real estate loans - Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	116,116	123,231
Ameriana | Real estate loans - Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	13,390	14,261
Ameriana | Individuals' loans for household and other personal expenditures
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	1,433	1,731
Ameriana | Other commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	1,840	1,928
C Financial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	94,308	99,166
Carrying Amount	92,097	96,829
Carrying Amount Net of Allowance	92,097	96,829
C Financial | Commercial and industrial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	99	104
C Financial | Real estate loans - Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	6,928	6,214
C Financial | Real estate loans - Commercial and farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	25,729	27,838
C Financial | Real estate loans - Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	52,720	55,856
C Financial | Real estate loans - Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	8,824	9,144
C Financial | Individuals' loans for household and other personal expenditures
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	8	10
Community
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	93,530	99,541
Carrying Amount	87,523	93,355
Allowance	105	4
Carrying Amount Net of Allowance	87,418	93,351
Community | Commercial and industrial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	7,224	6,769
Community | Agricultural production financing and other loans to farmers
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	2,472	1,761
Community | Real estate loans - Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	9,681	10,436
Community | Real estate loans - Commercial and farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	47,190	49,997
Community | Real estate loans - Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	19,212	21,886
Community | Real estate loans - Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	7,445	8,231
Community | Individuals' loans for household and other personal expenditures
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	306	461
CFS
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	371,786	393,014
Carrying Amount	353,882	373,649
Allowance	50	149
Carrying Amount Net of Allowance	353,832	373,500
CFS | Commercial and industrial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	50,476	52,060
CFS | Real estate loans - Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	862	976
CFS | Real estate loans - Commercial and farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	175,692	189,372
CFS | Real estate loans - Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	113,633	118,105
CFS | Real estate loans - Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	30,705	31,986
CFS | Individuals' loans for household and other personal expenditures
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	348	443
CFS | Other commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	70	72
SCB
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	36,796	38,743
Carrying Amount	32,390	34,092
Carrying Amount Net of Allowance	32,390	34,092
SCB | Commercial and industrial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	4,351	4,620
SCB | Agricultural production financing and other loans to farmers
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	1,263	1,288
SCB | Real estate loans - Commercial and farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	12,494	13,293
SCB | Real estate loans - Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	5,645	6,063
SCB | Real estate loans - Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	13,000	13,431
SCB | Individuals' loans for household and other personal expenditures
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	$ 43	$ 48