Loans Schedule of Recorded Investment in Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	$ 125,681		$ 125,681		$ 120,387
Recorded Investment With No Allowance	46,800		46,800		56,236
Recorded Investment With Allowance	52,342		52,342		35,729
Total Recorded Investment	99,142		99,142		91,965
Related Allowance	18,565		18,565		11,575
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	81,974	$ 82,674	82,798	$ 80,836
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Income Recognized	192	305	414	860
Interest Income on Impaired Loans If Interest Had Been Accrued	993	998	2,994	2,932
Commercial real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	58,137		58,137		58,179
Recorded Investment With No Allowance	16,518		16,518		27,882
Recorded Investment With Allowance	29,451		29,451		17,614
Total Recorded Investment	45,969		45,969		45,496
Related Allowance	5,868		5,868		3,401
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	33,408	36,075	35,572	38,639
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Income Recognized	100	226	241	587
Land acquisition & development construction real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	12,922		12,922		15,503
Recorded Investment With No Allowance	4,774		4,774		7,245
Recorded Investment With Allowance	1,785		1,785		778
Total Recorded Investment	6,559		6,559		8,023
Related Allowance	828		828		282
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	6,797	9,325	6,992	9,591
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Income Recognized	13	29	32	51
Residential construction real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	977		977		992
Recorded Investment With No Allowance	266		266		293
Recorded Investment With Allowance	0		0		0
Total Recorded Investment	266		266		293
Related Allowance	0		0		0
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	274	330	279	300
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Income Recognized	0	0	0	0
Commercial construction real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	1,154		1,154		1,264
Recorded Investment With No Allowance	232		232		340
Recorded Investment With Allowance	703		703		739
Total Recorded Investment	935		935		1,079
Related Allowance	737		737		739
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	1,055	2,339	1,007	1,902
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Income Recognized	1	4	3	6
Total construction loans
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	15,053		15,053		17,759
Recorded Investment With No Allowance	5,272		5,272		7,878
Recorded Investment With Allowance	2,488		2,488		1,517
Total Recorded Investment	7,760		7,760		9,395
Related Allowance	1,565		1,565		1,021
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	8,126	11,994	8,278	11,793
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Income Recognized	14	33	35	57
Residential real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	5,229		5,229		7,073
Recorded Investment With No Allowance	2,774		2,774		3,547
Recorded Investment With Allowance	1,043		1,043		2,317
Total Recorded Investment	3,817		3,817		5,864
Related Allowance	142		142		367
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	3,282	2,607	4,219	2,720
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Income Recognized	4	4	7	6
Agricultural real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	3,988		3,988		6,434
Recorded Investment With No Allowance	3,646		3,646		5,563
Recorded Investment With Allowance	26		26		198
Total Recorded Investment	3,672		3,672		5,761
Related Allowance	1		1		5
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	4,786	8,578	4,607	8,661
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Income Recognized	2	27	3	62
Total real estate loans
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	82,407		82,407		89,445
Recorded Investment With No Allowance	28,210		28,210		44,870
Recorded Investment With Allowance	33,008		33,008		21,646
Total Recorded Investment	61,218		61,218		66,516
Related Allowance	7,576		7,576		4,794
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	49,602	59,254	52,676	61,813
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Income Recognized	120	290	286	712
Commercial
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	39,349		39,349		29,593
Recorded Investment With No Allowance	15,296		15,296		10,744
Recorded Investment With Allowance	18,893		18,893		13,727
Total Recorded Investment	34,189		34,189		24,471
Related Allowance	10,912		10,912		6,487
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	30,123	22,483	27,781	18,175
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Income Recognized	72	2	128	122
Agricultural
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	3,925		3,925		1,349
Recorded Investment With No Allowance	3,294		3,294		622
Recorded Investment With Allowance	441		441		356
Total Recorded Investment	3,735		3,735		978
Related Allowance	77		77		$ 294
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	2,249	937	2,341	848
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Income Recognized	$ 0	$ 13	$ 0	$ 26