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Allowance for Probable Loan Losses (Details 6) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Loan portfolio by credit quality indicator
Portfolio, total	$ 5,774,462	$ 5,679,245
Pass
Loan portfolio by credit quality indicator
Portfolio, total	5,436,564	5,328,410
Special Review
Loan portfolio by credit quality indicator
Portfolio, total	4,734	54,561
Watch List - Pass
Loan portfolio by credit quality indicator
Portfolio, total	49,174	37,674
Watch List - Substandard
Loan portfolio by credit quality indicator
Portfolio, total	225,459	182,429
Watch List - Impaired
Loan portfolio by credit quality indicator
Portfolio, total	58,531	76,171
Commercial
Loan portfolio by credit quality indicator
Portfolio, total	1,030,568	1,089,486
Commercial | Pass
Loan portfolio by credit quality indicator
Portfolio, total	892,149	961,490
Commercial | Special Review
Loan portfolio by credit quality indicator
Portfolio, total		38,382
Commercial | Watch List - Pass
Loan portfolio by credit quality indicator
Portfolio, total	23,033	3,793
Commercial | Watch List - Substandard
Loan portfolio by credit quality indicator
Portfolio, total	82,188	45,646
Commercial | Watch List - Impaired
Loan portfolio by credit quality indicator
Portfolio, total	33,198	40,175
Commercial Real Estate: Other Construction and Land Development
Loan portfolio by credit quality indicator
Portfolio, total	1,556,880	1,414,977
Commercial Real Estate: Other Construction and Land Development | Pass
Loan portfolio by credit quality indicator
Portfolio, total	1,505,229	1,353,971
Commercial Real Estate: Other Construction and Land Development | Special Review
Loan portfolio by credit quality indicator
Portfolio, total	331	1,005
Commercial Real Estate: Other Construction and Land Development | Watch List - Pass
Loan portfolio by credit quality indicator
Portfolio, total	5,995	10,428
Commercial Real Estate: Other Construction and Land Development | Watch List - Substandard
Loan portfolio by credit quality indicator
Portfolio, total	38,637	38,697
Commercial Real Estate: Other Construction and Land Development | Watch List - Impaired
Loan portfolio by credit quality indicator
Portfolio, total	6,688	10,876
Commercial real estate: farmland and commercial
Loan portfolio by credit quality indicator
Portfolio, total	1,917,665	1,901,399
Commercial real estate: farmland and commercial | Pass
Loan portfolio by credit quality indicator
Portfolio, total	1,783,224	1,754,741
Commercial real estate: farmland and commercial | Special Review
Loan portfolio by credit quality indicator
Portfolio, total	4,403	11,674
Commercial real estate: farmland and commercial | Watch List - Pass
Loan portfolio by credit quality indicator
Portfolio, total	19,654	23,453
Commercial real estate: farmland and commercial | Watch List - Substandard
Loan portfolio by credit quality indicator
Portfolio, total	100,755	97,365
Commercial real estate: farmland and commercial | Watch List - Impaired
Loan portfolio by credit quality indicator
Portfolio, total	9,629	14,166
Commercial real estate: multifamily
Loan portfolio by credit quality indicator
Portfolio, total	94,003	116,699
Commercial real estate: multifamily | Pass
Loan portfolio by credit quality indicator
Portfolio, total	93,041	115,729
Commercial real estate: multifamily | Watch List - Substandard
Loan portfolio by credit quality indicator
Portfolio, total	135	135
Commercial real estate: multifamily | Watch List - Impaired
Loan portfolio by credit quality indicator
Portfolio, total	827	835
Residential: first lien
Loan portfolio by credit quality indicator
Portfolio, total	414,463	422,026
Residential: first lien | Pass
Loan portfolio by credit quality indicator
Portfolio, total	405,116	412,668
Residential: first lien | Special Review
Loan portfolio by credit quality indicator
Portfolio, total		3,500
Residential: first lien | Watch List - Pass
Loan portfolio by credit quality indicator
Portfolio, total	492
Residential: first lien | Watch List - Substandard
Loan portfolio by credit quality indicator
Portfolio, total	3,483	18
Residential: first lien | Watch List - Impaired
Loan portfolio by credit quality indicator
Portfolio, total	5,372	5,840
Residential: junior lien
Loan portfolio by credit quality indicator
Portfolio, total	513,767	488,300
Residential: junior lien | Pass
Loan portfolio by credit quality indicator
Portfolio, total	512,246	484,968
Residential: junior lien | Watch List - Substandard
Loan portfolio by credit quality indicator
Portfolio, total	261	437
Residential: junior lien | Watch List - Impaired
Loan portfolio by credit quality indicator
Portfolio, total	1,260	2,895
Consumer
Loan portfolio by credit quality indicator
Portfolio, total	57,966	61,137
Consumer | Pass
Loan portfolio by credit quality indicator
Portfolio, total	56,808	59,622
Consumer | Watch List - Substandard
Loan portfolio by credit quality indicator
Portfolio, total		131
Consumer | Watch List - Impaired
Loan portfolio by credit quality indicator
Portfolio, total	1,158	1,384
Foreign
Loan portfolio by credit quality indicator
Portfolio, total	189,150	185,221
Foreign | Pass
Loan portfolio by credit quality indicator
Portfolio, total	188,751	$ 185,221
Foreign | Watch List - Impaired
Loan portfolio by credit quality indicator
Portfolio, total	$ 399

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Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

+ References

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



-Publisher FASB



-Name Accounting Standards Codification



-Topic 310



-SubTopic 10



-Section 45



-Paragraph 2



-URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522



Reference 2: http://www.xbrl.org/2003/role/presentationRef



-Publisher FASB



-Name Accounting Standards Codification



-Topic 310



-SubTopic 10



-Section 50



-Paragraph 4



-URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5074-111524

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