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Allowance for Probable Loan Losses (Details 4) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Interest Recognized
Total trouble debt restructuring	$ 15,287		$ 15,287		$ 15,653
Period of charge off for past due unsecured commercial loans			90 days
Class of financing receivable
Recorded investment:
Total impaired loans with related allowance	18,811		$ 18,811		31,765
Total impaired loans with no related allowance	39,720		39,720		44,406
Unpaid principal balance:
Total impaired loans with an allowance recorded	29,094		29,094		32,232
Total impaired loans with no related allowance recorded	42,088		42,088		46,262
Related Allowance	2,847		2,847		12,221
Average recorded investment:
Total impaired loans with an allowance recorded	22,306	$ 30,955	27,126	$ 30,882	33,286
Total impaired loans with no related allowance recorded	39,723	45,663	40,606	44,882	43,202
Interest Recognized
Total impaired loans with an allowance recorded	23	23	46	46	92
Total impaired loans with no related allowance recorded	105	114	212	224	444
Commercial
Interest Recognized
Total trouble debt restructuring	2,446		2,446		2,500
Commercial | Class of financing receivable
Recorded investment:
Total impaired loans with related allowance	11,780		11,780		19,944
Total impaired loans with no related allowance	21,418		21,418		20,231
Unpaid principal balance:
Total impaired loans with an allowance recorded	21,862		21,862		20,026
Total impaired loans with no related allowance recorded	22,303		22,303		20,260
Related Allowance	1,200		1,200		9,112
Average recorded investment:
Total impaired loans with an allowance recorded	15,121	17,685	17,828	17,486	19,313
Total impaired loans with no related allowance recorded	20,752	20,347	20,288	18,704	18,563
Interest Recognized
Total impaired loans with no related allowance recorded	1	1	2	2	4
Commercial Real Estate: Other Construction and Land Development
Interest Recognized
Total trouble debt restructuring	2,254		2,254		2,254
Commercial Real Estate: Other Construction and Land Development | Class of financing receivable
Recorded investment:
Total impaired loans with related allowance	3,502		3,502		6,714
Total impaired loans with no related allowance	3,186		3,186		4,162
Unpaid principal balance:
Total impaired loans with an allowance recorded	3,502		3,502		6,949
Total impaired loans with no related allowance recorded	3,499		3,499		4,270
Related Allowance	1,142		1,142		1,890
Average recorded investment:
Total impaired loans with an allowance recorded	3,652	6,896	4,988	6,897	7,183
Total impaired loans with no related allowance recorded	3,291	5,226	3,451	6,014	4,882
Interest Recognized
Total impaired loans with no related allowance recorded	19	19	37	37	74
Commercial real estate: farmland and commercial
Interest Recognized
Total trouble debt restructuring	2,853		2,853		2,861
Commercial real estate: farmland and commercial | Class of financing receivable
Recorded investment:
Total impaired loans with related allowance	3,529		3,529		5,107
Total impaired loans with no related allowance	6,100		6,100		9,059
Unpaid principal balance:
Total impaired loans with an allowance recorded	3,730		3,730		5,257
Total impaired loans with no related allowance recorded	7,191		7,191		10,562
Related Allowance	505		505		1,219
Average recorded investment:
Total impaired loans with an allowance recorded	3,533	6,374	4,310	6,499	6,790
Total impaired loans with no related allowance recorded	6,688	8,854	7,778	8,755	8,664
Interest Recognized
Total impaired loans with an allowance recorded	23	23	46	46	92
Commercial real estate: multifamily
Interest Recognized
Total trouble debt restructuring	21		21
Commercial real estate: multifamily | Class of financing receivable
Recorded investment:
Total impaired loans with no related allowance	827		827		835
Unpaid principal balance:
Total impaired loans with no related allowance recorded	827		827		835
Average recorded investment:
Total impaired loans with no related allowance recorded	832	270	839	278	363
Interest Recognized
Total impaired loans with no related allowance recorded			1
Residential: first lien
Interest Recognized
Total trouble debt restructuring	4,950		4,950		5,313
Residential: first lien | Class of financing receivable
Recorded investment:
Total impaired loans with no related allowance	5,372		5,372		5,840
Unpaid principal balance:
Total impaired loans with no related allowance recorded	5,430		5,430		6,034
Average recorded investment:
Total impaired loans with no related allowance recorded	5,289	6,057	5,329	6,172	6,293
Interest Recognized
Total impaired loans with no related allowance recorded	61	64	123	127	273
Residential: junior lien
Interest Recognized
Total trouble debt restructuring	1,241		1,241		1,371
Residential: junior lien | Class of financing receivable
Recorded investment:
Total impaired loans with no related allowance	1,260		1,260		2,895
Unpaid principal balance:
Total impaired loans with no related allowance recorded	1,281		1,281		2,915
Average recorded investment:
Total impaired loans with no related allowance recorded	1,317	3,114	1,346	3,124	3,035
Interest Recognized
Total impaired loans with no related allowance recorded	19	24	39	47	90
Consumer
Interest Recognized
Total trouble debt restructuring	1,123		1,123		1,354
Consumer | Class of financing receivable
Recorded investment:
Total impaired loans with no related allowance	1,158		1,158		1,384
Unpaid principal balance:
Total impaired loans with no related allowance recorded	1,158		1,158		1,386
Average recorded investment:
Total impaired loans with no related allowance recorded	1,153	1,369	1,171	1,406	1,402
Interest Recognized
Total impaired loans with no related allowance recorded	1	1	1	2	$ 3
Foreign
Interest Recognized
Total trouble debt restructuring	399		399
Foreign | Class of financing receivable
Recorded investment:
Total impaired loans with no related allowance	399		399
Unpaid principal balance:
Total impaired loans with no related allowance recorded	399		399
Average recorded investment:
Total impaired loans with no related allowance recorded	401	426	404	429
Interest Recognized
Total impaired loans with no related allowance recorded	$ 4	$ 5	$ 9	$ 9

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