Loans - Schedule of Recorded Investment in Impaired Loans (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	$ 120,387	$ 87,240	$ 124,867
Recorded Investment With No Allowance	56,236	57,050	62,724
Recorded Investment With Allowance	35,729	21,430	47,848
Total Recorded Investment	91,965	78,480	110,572
Related Allowance	11,575	5,792	8,929
Impaired Financing Receivable, Average Recorded Investment	80,310	97,655	123,376
Impaired Financing Receivable, Interest Income, Cash Basis Method	1,034	1,083	1,692
Impaired Loans, interest lost on nonaccrual loans	3,935	4,951	5,786
Commercial real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	58,179	41,603	64,780
Recorded Investment With No Allowance	27,882	28,143	29,216
Recorded Investment With Allowance	17,614	11,246	33,937
Total Recorded Investment	45,496	39,389	63,153
Related Allowance	3,401	1,608	5,210
Impaired Financing Receivable, Average Recorded Investment	39,233	54,701	66,330
Impaired Financing Receivable, Interest Income, Cash Basis Method	784	876	1,092
Land acquisition & development construction real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	15,503	12,511	23,906
Recorded Investment With No Allowance	7,245	7,262	9,901
Recorded Investment With Allowance	778	1,615	7,226
Total Recorded Investment	8,023	8,877	17,127
Related Allowance	282	574	1,434
Impaired Financing Receivable, Average Recorded Investment	8,337	13,056	19,523
Impaired Financing Receivable, Interest Income, Cash Basis Method	54	43	487
Residential construction real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	992	459	1,816
Recorded Investment With No Allowance	293	272	1,095
Recorded Investment With Allowance	0	0	277
Total Recorded Investment	293	272	1,372
Related Allowance	0	0	26
Impaired Financing Receivable, Average Recorded Investment	282	822	1,893
Impaired Financing Receivable, Interest Income, Cash Basis Method	0	0	0
Commercial Construction
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	1,264	2,729	397
Recorded Investment With No Allowance	340	253	279
Recorded Investment With Allowance	739	2,442	84
Total Recorded Investment	1,079	2,695	363
Related Allowance	739	904	85
Impaired Financing Receivable, Average Recorded Investment	1,887	1,529	3,936
Impaired Financing Receivable, Interest Income, Cash Basis Method	7	8	4
Total construction loans
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	17,759	15,699	26,119
Recorded Investment With No Allowance	7,878	7,787	11,275
Recorded Investment With Allowance	1,517	4,057	7,587
Total Recorded Investment	9,395	11,844	18,862
Related Allowance	1,021	1,478	1,545
Impaired Financing Receivable, Average Recorded Investment	10,506	15,407	25,352
Impaired Financing Receivable, Interest Income, Cash Basis Method	61	51	491
Residential real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	7,073	2,959	9,448
Recorded Investment With No Allowance	3,547	2,452	5,081
Recorded Investment With Allowance	2,317	341	967
Total Recorded Investment	5,864	2,793	6,048
Related Allowance	367	143	249
Impaired Financing Receivable, Average Recorded Investment	4,055	4,537	8,104
Impaired Financing Receivable, Interest Income, Cash Basis Method	1	5	17
Agricultural real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	6,434	8,844	8,895
Recorded Investment With No Allowance	5,563	6,444	6,429
Recorded Investment With Allowance	198	2,305	2,370
Total Recorded Investment	5,761	8,749	8,799
Related Allowance	5	732	335
Impaired Financing Receivable, Average Recorded Investment	7,156	8,774	8,230
Impaired Financing Receivable, Interest Income, Cash Basis Method	39	78	8
Total real estate loans
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	89,445	69,105	109,242
Recorded Investment With No Allowance	44,870	44,826	52,001
Recorded Investment With Allowance	21,646	17,949	44,861
Total Recorded Investment	66,516	62,775	96,862
Related Allowance	4,794	3,961	7,339
Impaired Financing Receivable, Average Recorded Investment	60,950	83,419	108,016
Impaired Financing Receivable, Interest Income, Cash Basis Method	885	1,010	1,608
Commercial
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	29,593	16,904	15,448
Recorded Investment With No Allowance	10,744	11,882	10,684
Recorded Investment With Allowance	13,727	2,644	2,901
Total Recorded Investment	24,471	14,526	13,585
Related Allowance	6,487	1,190	1,504
Impaired Financing Receivable, Average Recorded Investment	18,502	13,789	15,047
Impaired Financing Receivable, Interest Income, Cash Basis Method	123	50	68
Agricultural
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	1,349	1,231	177
Recorded Investment With No Allowance	622	342	39
Recorded Investment With Allowance	356	837	86
Total Recorded Investment	978	1,179	125
Related Allowance	294	641	86
Impaired Financing Receivable, Average Recorded Investment	858	447	313
Impaired Financing Receivable, Interest Income, Cash Basis Method	$ 26	$ 23	$ 16

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=49124121&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=49124121&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=49124121&loc=SL6953550-111524

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Amount of allowance for credit losses related to recorded investment.

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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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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).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=25495931&loc=d3e18794-111554

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