Allowance for Probable Loan Losses (Aging By Loan Class) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Financing receivable recorded investment
Past due	$ 52,633	$ 61,400
Past due 90 days or Greater and Still Accruing	6,663	5,226
Loans, current	6,153,213	5,903,288
Total loans	6,205,846	5,964,688
30 to 59 Days
Financing receivable recorded investment
Past due	14,839	17,299
60 to 89 Days
Financing receivable recorded investment
Past due	4,687	6,327
90 Days or Greater
Financing receivable recorded investment
Past due	33,107	37,774
Commercial
Financing receivable recorded investment
Past due	23,095	26,033
Past due 90 days or Greater and Still Accruing	768	392
Loans, current	891,008	883,634
Total loans	914,103	909,667
Commercial \| 30 to 59 Days
Financing receivable recorded investment
Past due	2,351	4,081
Commercial \| 60 to 89 Days
Financing receivable recorded investment
Past due	406	829
Commercial \| 90 Days or Greater
Financing receivable recorded investment
Past due	20,338	21,123
Commercial Real Estate: Other Construction and Land Development
Financing receivable recorded investment
Past due	3,554	6,354
Past due 90 days or Greater and Still Accruing	65	9
Loans, current	1,834,720	1,710,521
Total loans	1,838,274	1,716,875
Commercial Real Estate: Other Construction and Land Development \| 30 to 59 Days
Financing receivable recorded investment
Past due	1,095	1,502
Commercial Real Estate: Other Construction and Land Development \| 60 to 89 Days
Financing receivable recorded investment
Past due	1,367	396
Commercial Real Estate: Other Construction and Land Development \| 90 Days or Greater
Financing receivable recorded investment
Past due	1,092	4,456
Commercial Real Estate: Farmland & Commercial
Financing receivable recorded investment
Past due	9,883	12,658
Past due 90 days or Greater and Still Accruing	480	289
Loans, current	1,950,477	1,930,412
Total loans	1,960,360	1,943,070
Commercial Real Estate: Farmland & Commercial \| 30 to 59 Days
Financing receivable recorded investment
Past due	4,702	3,454
Commercial Real Estate: Farmland & Commercial \| 60 to 89 Days
Financing receivable recorded investment
Past due	486	3,054
Commercial Real Estate: Farmland & Commercial \| 90 Days or Greater
Financing receivable recorded investment
Past due	4,695	6,150
Commercial Real Estate: Multifamily
Financing receivable recorded investment
Past due	1,365	596
Loans, current	175,228	139,870
Total loans	176,593	140,466
Commercial Real Estate: Multifamily \| 30 to 59 Days
Financing receivable recorded investment
Past due		44
Commercial Real Estate: Multifamily \| 60 to 89 Days
Financing receivable recorded investment
Past due	850
Commercial Real Estate: Multifamily \| 90 Days or Greater
Financing receivable recorded investment
Past due	515	552
Residential First Lien
Financing receivable recorded investment
Past due	8,811	11,108
Past due 90 days or Greater and Still Accruing	3,957	3,756
Loans, current	411,834	410,796
Total loans	420,645	421,904
Residential First Lien \| 30 to 59 Days
Financing receivable recorded investment
Past due	3,613	5,615
Residential First Lien \| 60 to 89 Days
Financing receivable recorded investment
Past due	748	1,350
Residential First Lien \| 90 Days or Greater
Financing receivable recorded investment
Past due	4,450	4,143
Residential Junior Lien
Financing receivable recorded investment
Past due	1,944	1,480
Past due 90 days or Greater and Still Accruing	761	382
Loans, current	656,176	608,838
Total loans	658,120	610,318
Residential Junior Lien \| 30 to 59 Days
Financing receivable recorded investment
Past due	669	762
Residential Junior Lien \| 60 to 89 Days
Financing receivable recorded investment
Past due	342	178
Residential Junior Lien \| 90 Days or Greater
Financing receivable recorded investment
Past due	933	540
Consumer
Financing receivable recorded investment
Past due	1,495	1,418
Past due 90 days or Greater and Still Accruing	379	387
Loans, current	52,038	53,750
Total loans	53,533	55,168
Consumer \| 30 to 59 Days
Financing receivable recorded investment
Past due	877	910
Consumer \| 60 to 89 Days
Financing receivable recorded investment
Past due	181	95
Consumer \| 90 Days or Greater
Financing receivable recorded investment
Past due	437	413
Foreign
Financing receivable recorded investment
Past due	2,486	1,753
Past due 90 days or Greater and Still Accruing	253	11
Loans, current	181,732	165,467
Total loans	184,218	167,220
Foreign \| 30 to 59 Days
Financing receivable recorded investment
Past due	1,532	931
Foreign \| 60 to 89 Days
Financing receivable recorded investment
Past due	307	425
Foreign \| 90 Days or Greater
Financing receivable recorded investment
Past due	$ 647	$ 397

Recorded investment in financing receivables that are 90 days or more past due and still accruing.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Recorded Investment
-URI http://asc.fasb.org/extlink&oid=65880944

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5111-111524

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Financing receivables that are current.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7A
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953401-111524

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Recorded Investment in financing receivables that are past due at the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Recorded Investment
-URI http://asc.fasb.org/extlink&oid=65880944

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7A
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953401-111524

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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=65884687&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=66008989&loc=d3e5074-111524

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