Accounting for Certain Loans Acquired in a Purchase - Carrying Amount of Loans Included in Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	$ 671,239	$ 698,457
Carrying Amount	636,582	658,471
Allowance	311	650
Carrying Amount Net of Allowance	636,271	657,821
Loans acquired and accounted for under ASC 310-30, outstanding balance	82,900	99,000
Loans acquired and accounted for under ASC 310-30, carrying amount	62,000	73,100
Commercial and industrial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	67,672	79,124
Agricultural production financing and other loans to farmers
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	3,480	1,993
Real estate loans - Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	16,828	28,176
Real estate loans - Commercial and farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	305,420	341,195
Real estate loans - Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	210,379	180,643
Real estate loans - Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	66,211	64,883
Individuals' loans for household and other personal expenditures
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	1,176	2,357
Other commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	73	86
C Financial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	102,381
Carrying Amount	$ 100,001
Allowance
Carrying Amount Net of Allowance	$ 100,001
C Financial | Commercial and industrial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	$ 109
C Financial | Agricultural production financing and other loans to farmers
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired
C Financial | Real estate loans - Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	$ 6,209
C Financial | Real estate loans - Commercial and farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	28,094
C Financial | Real estate loans - Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	58,096
C Financial | Real estate loans - Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	9,861
C Financial | Individuals' loans for household and other personal expenditures
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	$ 12
C Financial | Other commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired
Community
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	$ 105,948	142,989
Carrying Amount	99,467	$ 134,198
Allowance	109
Carrying Amount Net of Allowance	99,358	$ 134,198
Community | Commercial and industrial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	6,628	8,168
Community | Agricultural production financing and other loans to farmers
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	2,024	1,100
Community | Real estate loans - Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	8,959	19,063
Community | Real estate loans - Commercial and farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	56,148	74,600
Community | Real estate loans - Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	23,465	28,863
Community | Real estate loans - Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	8,147	9,881
Community | Individuals' loans for household and other personal expenditures
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	$ 577	$ 1,314
Community | Other commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired
CFS
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	$ 422,161	$ 509,660
Carrying Amount	401,497	484,949
Allowance	202	650
Carrying Amount Net of Allowance	401,295	484,299
CFS | Commercial and industrial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	$ 55,927	64,897
CFS | Agricultural production financing and other loans to farmers
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired
CFS | Real estate loans - Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	$ 1,660	9,113
CFS | Real estate loans - Commercial and farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	207,197	251,002
CFS | Real estate loans - Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	122,369	144,396
CFS | Real estate loans - Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	34,404	39,244
CFS | Individuals' loans for household and other personal expenditures
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	531	922
CFS | Other commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	73	86
SCB
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	40,749	45,808
Carrying Amount	$ 35,617	$ 39,324
Allowance
Carrying Amount Net of Allowance	$ 35,617	$ 39,324
SCB | Commercial and industrial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	5,008	6,059
SCB | Agricultural production financing and other loans to farmers
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	1,456	893
SCB | Real estate loans - Commercial and farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	13,981	15,593
SCB | Real estate loans - Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	6,449	7,384
SCB | Real estate loans - Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	13,799	15,758
SCB | Individuals' loans for household and other personal expenditures
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired	$ 56	$ 121
SCB | Other commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Acquired