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Allowance for Probable Loan Losses (Portfolio Credit Quality By Loan Class) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Loan portfolio by credit quality indicator
Portfolio, total	$ 5,951,597	$ 5,950,914
Pass
Loan portfolio by credit quality indicator
Portfolio, total	5,558,419	5,529,707
Special Review
Loan portfolio by credit quality indicator
Portfolio, total	1,011	45,599
Watch List - Pass
Loan portfolio by credit quality indicator
Portfolio, total	148,243	83,069
Watch List - Substandard
Loan portfolio by credit quality indicator
Portfolio, total	206,201	232,091
Watch - List Impaired
Loan portfolio by credit quality indicator
Portfolio, total	37,723	60,448
Commercial
Loan portfolio by credit quality indicator
Portfolio, total	941,952	966,852
Commercial | Pass
Loan portfolio by credit quality indicator
Portfolio, total	769,116	771,999
Commercial | Special Review
Loan portfolio by credit quality indicator
Portfolio, total		42,152
Commercial | Watch List - Pass
Loan portfolio by credit quality indicator
Portfolio, total	90,274	31,539
Commercial | Watch List - Substandard
Loan portfolio by credit quality indicator
Portfolio, total	69,411	90,215
Commercial | Watch - List Impaired
Loan portfolio by credit quality indicator
Portfolio, total	13,151	30,946
Commercial Real Estate: Other Construction and Land Development
Loan portfolio by credit quality indicator
Portfolio, total	1,686,111	1,649,827
Commercial Real Estate: Other Construction and Land Development | Pass
Loan portfolio by credit quality indicator
Portfolio, total	1,620,286	1,582,683
Commercial Real Estate: Other Construction and Land Development | Special Review
Loan portfolio by credit quality indicator
Portfolio, total		1,164
Commercial Real Estate: Other Construction and Land Development | Watch List - Pass
Loan portfolio by credit quality indicator
Portfolio, total	15,502	13,765
Commercial Real Estate: Other Construction and Land Development | Watch List - Substandard
Loan portfolio by credit quality indicator
Portfolio, total	46,173	45,994
Commercial Real Estate: Other Construction and Land Development | Watch - List Impaired
Loan portfolio by credit quality indicator
Portfolio, total	4,150	6,221
Commercial Real Estate: Farmland & Commercial
Loan portfolio by credit quality indicator
Portfolio, total	1,953,771	1,995,448
Commercial Real Estate: Farmland & Commercial | Pass
Loan portfolio by credit quality indicator
Portfolio, total	1,814,127	1,849,587
Commercial Real Estate: Farmland & Commercial | Special Review
Loan portfolio by credit quality indicator
Portfolio, total	1,011	2,283
Commercial Real Estate: Farmland & Commercial | Watch List - Pass
Loan portfolio by credit quality indicator
Portfolio, total	38,050	37,765
Commercial Real Estate: Farmland & Commercial | Watch List - Substandard
Loan portfolio by credit quality indicator
Portfolio, total	90,340	92,008
Commercial Real Estate: Farmland & Commercial | Watch - List Impaired
Loan portfolio by credit quality indicator
Portfolio, total	10,243	13,806
Commercial Real Estate: Multifamily
Loan portfolio by credit quality indicator
Portfolio, total	139,426	139,448
Commercial Real Estate: Multifamily | Pass
Loan portfolio by credit quality indicator
Portfolio, total	138,714	138,546
Commercial Real Estate: Multifamily | Watch List - Substandard
Loan portfolio by credit quality indicator
Portfolio, total	122	125
Commercial Real Estate: Multifamily | Watch - List Impaired
Loan portfolio by credit quality indicator
Portfolio, total	590	777
Residential First Lien
Loan portfolio by credit quality indicator
Portfolio, total	415,876	410,244
Residential First Lien | Pass
Loan portfolio by credit quality indicator
Portfolio, total	404,862	401,053
Residential First Lien | Watch List - Pass
Loan portfolio by credit quality indicator
Portfolio, total	4,177
Residential First Lien | Watch List - Substandard
Loan portfolio by credit quality indicator
Portfolio, total	154	3,492
Residential First Lien | Watch - List Impaired
Loan portfolio by credit quality indicator
Portfolio, total	6,683	5,699
Residential Junior Lien
Loan portfolio by credit quality indicator
Portfolio, total	581,433	552,338
Residential Junior Lien | Pass
Loan portfolio by credit quality indicator
Portfolio, total	580,172	551,138
Residential Junior Lien | Watch List - Pass
Loan portfolio by credit quality indicator
Portfolio, total	240
Residential Junior Lien | Watch List - Substandard
Loan portfolio by credit quality indicator
Portfolio, total		250
Residential Junior Lien | Watch - List Impaired
Loan portfolio by credit quality indicator
Portfolio, total	1,021	950
Consumer
Loan portfolio by credit quality indicator
Portfolio, total	56,117	57,744
Consumer | Pass
Loan portfolio by credit quality indicator
Portfolio, total	54,984	56,440
Consumer | Watch List - Substandard
Loan portfolio by credit quality indicator
Portfolio, total	1	7
Consumer | Watch - List Impaired
Loan portfolio by credit quality indicator
Portfolio, total	1,132	1,297
Foreign
Loan portfolio by credit quality indicator
Portfolio, total	176,911	179,013
Foreign | Pass
Loan portfolio by credit quality indicator
Portfolio, total	176,158	178,261
Foreign | Watch - List Impaired
Loan portfolio by credit quality indicator
Portfolio, total	$ 753	$ 752

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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=49124121&loc=d3e5074-111524

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