Loans and Allowance - Summary of Troubled Debt Restructurings (Details) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2017 USD ($) loan	Sep. 30, 2016 USD ($) loan	Sep. 30, 2017 USD ($) loan	Sep. 30, 2016 USD ($) loan
Financing Receivable, Modifications [Line Items]
Pre-Modification Recorded Balance	$ 194	$ 753	$ 1,517	$ 6,797
Post-Modification Recorded Balance	$ 201	$ 831	$ 1,261	$ 6,702
Number of Loans \| loan	4	14	18	32
Commercial and industrial loans
Financing Receivable, Modifications [Line Items]
Pre-Modification Recorded Balance	$ 6		$ 400	$ 260
Post-Modification Recorded Balance	$ 6		$ 176	$ 260
Number of Loans \| loan	1		2	3
Agricultural production financing and other loans to farmers
Financing Receivable, Modifications [Line Items]
Pre-Modification Recorded Balance				$ 1,606
Post-Modification Recorded Balance				$ 1,472
Number of Loans \| loan				5
Real estate loans - Commercial and farmland
Financing Receivable, Modifications [Line Items]
Pre-Modification Recorded Balance		$ 87	$ 357	$ 3,978
Post-Modification Recorded Balance		$ 95	$ 492	$ 3,955
Number of Loans \| loan		1	6	7
Real estate loans - Residential
Financing Receivable, Modifications [Line Items]
Pre-Modification Recorded Balance	$ 120	$ 611	$ 570	$ 724
Post-Modification Recorded Balance	$ 122	$ 678	$ 520	$ 811
Number of Loans \| loan	1	11	8	14
Real estate loans - Home equity
Financing Receivable, Modifications [Line Items]
Pre-Modification Recorded Balance	$ 68	$ 55	$ 190	$ 229
Post-Modification Recorded Balance	$ 73	$ 58	$ 73	$ 204
Number of Loans \| loan	2	2	2	3

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Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953676-111524

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