Loans - Schedule of Recorded Investment in Impaired Loans (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	$ 132,785	$ 120,387	$ 87,240
Recorded Investment With No Allowance	57,992	56,236	57,050
Recorded Investment With Allowance	46,699	35,729	21,430
Total Recorded Investment	104,691	91,965	78,480
Related Allowance	13,954	11,575	5,792
Impaired Financing Receivable, Average Recorded Investment	101,108	80,310	97,655
Impaired Financing Receivable, Interest Income, Cash Basis Method	672	1,034	1,083
Impaired Loans, interest lost on nonaccrual loans	4,203	3,935	4,951
Commercial real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	57,017	58,179	41,603
Recorded Investment With No Allowance	24,410	27,882	28,143
Recorded Investment With Allowance	21,420	17,614	11,246
Total Recorded Investment	45,830	45,496	39,389
Related Allowance	2,847	3,401	1,608
Impaired Financing Receivable, Average Recorded Investment	46,870	39,233	54,701
Impaired Financing Receivable, Interest Income, Cash Basis Method	239	784	876
Land acquisition & development construction real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	12,084	15,503	12,511
Recorded Investment With No Allowance	4,330	7,245	7,262
Recorded Investment With Allowance	1,813	778	1,615
Total Recorded Investment	6,143	8,023	8,877
Related Allowance	826	282	574
Impaired Financing Receivable, Average Recorded Investment	8,026	8,337	13,056
Impaired Financing Receivable, Interest Income, Cash Basis Method	40	54	43
Residential construction real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	1,555	992	459
Recorded Investment With No Allowance	219	293	272
Recorded Investment With Allowance	619	0	0
Total Recorded Investment	838	293	272
Related Allowance	1	0	0
Impaired Financing Receivable, Average Recorded Investment	829	282	822
Impaired Financing Receivable, Interest Income, Cash Basis Method	0	0	0
Commercial Construction
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	4,786	1,264	2,729
Recorded Investment With No Allowance	3,940	340	253
Recorded Investment With Allowance	647	739	2,442
Total Recorded Investment	4,587	1,079	2,695
Related Allowance	657	739	904
Impaired Financing Receivable, Average Recorded Investment	2,882	1,887	1,529
Impaired Financing Receivable, Interest Income, Cash Basis Method	24	7	8
Total construction loans
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	18,425	17,759	15,699
Recorded Investment With No Allowance	8,489	7,878	7,787
Recorded Investment With Allowance	3,079	1,517	4,057
Total Recorded Investment	11,568	9,395	11,844
Related Allowance	1,484	1,021	1,478
Impaired Financing Receivable, Average Recorded Investment	11,737	10,506	15,407
Impaired Financing Receivable, Interest Income, Cash Basis Method	64	61	51
Residential real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	8,222	7,073	2,959
Recorded Investment With No Allowance	4,074	3,547	2,452
Recorded Investment With Allowance	2,470	2,317	341
Total Recorded Investment	6,544	5,864	2,793
Related Allowance	253	367	143
Impaired Financing Receivable, Average Recorded Investment	6,220	4,055	4,537
Impaired Financing Receivable, Interest Income, Cash Basis Method	11	1	5
Agricultural real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	5,069	6,434	8,844
Recorded Investment With No Allowance	4,509	5,563	6,444
Recorded Investment With Allowance	181	198	2,305
Total Recorded Investment	4,690	5,761	8,749
Related Allowance	4	5	732
Impaired Financing Receivable, Average Recorded Investment	4,365	7,156	8,774
Impaired Financing Receivable, Interest Income, Cash Basis Method	16	39	78
Total real estate loans
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	88,733	89,445	69,105
Recorded Investment With No Allowance	41,482	44,870	44,826
Recorded Investment With Allowance	27,150	21,646	17,949
Total Recorded Investment	68,632	66,516	62,775
Related Allowance	4,588	4,794	3,961
Impaired Financing Receivable, Average Recorded Investment	69,192	60,950	83,419
Impaired Financing Receivable, Interest Income, Cash Basis Method	330	885	1,010
Commercial
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	40,314	29,593	16,904
Recorded Investment With No Allowance	13,230	10,744	11,882
Recorded Investment With Allowance	19,167	13,727	2,644
Total Recorded Investment	32,397	24,471	14,526
Related Allowance	9,254	6,487	1,190
Impaired Financing Receivable, Average Recorded Investment	30,089	18,502	13,789
Impaired Financing Receivable, Interest Income, Cash Basis Method	307	123	50
Agricultural
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	3,738	1,349	1,231
Recorded Investment With No Allowance	3,280	622	342
Recorded Investment With Allowance	382	356	837
Total Recorded Investment	3,662	978	1,179
Related Allowance	112	294	641
Impaired Financing Receivable, Average Recorded Investment	1,827	858	447
Impaired Financing Receivable, Interest Income, Cash Basis Method	$ 35	$ 26	$ 23

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5212-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5258-111524

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Amount of interest income recognized on a cash-basis method of accounting that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

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Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953550-111524

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Amount of allowance for credit losses related to recorded investment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Recorded Investment
-URI http://asc.fasb.org/extlink&oid=65880944

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
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-Section 50
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Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses.

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Amount of investment in impaired financing receivables for which there is no related allowance for credit losses.

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Amount of investment in impaired financing receivables for which there is a related allowance for credit losses.

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Reflects the amount of additional interest income that would have been recorded if impaired or nonperforming loans were instead current, in compliance with their original terms, and outstanding throughout the reporting period or since origination (if held for part of the period).

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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