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Allowance for Probable Loan Losses (Impairment By Loan Class) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	$ 47,591	$ 60,448
Loans Individually Evaluated for Impairment, Allowance	1,396	2,206
Loans Collectively Evaluated for Impairment, Recorded Investment	5,839,072	5,890,466
Loans Collectively Evaluated for Impairment, Allowance	62,574	64,782
Commercial
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	21,931	30,946
Loans Individually Evaluated for Impairment, Allowance	734	1,704
Loans Collectively Evaluated for Impairment, Recorded Investment	891,889	935,905
Loans Collectively Evaluated for Impairment, Allowance	25,156	19,727
Commercial Real Estate: Other Construction and Land Development
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	4,601	6,221
Loans Individually Evaluated for Impairment, Allowance	116	100
Loans Collectively Evaluated for Impairment, Recorded Investment	1,606,475	1,643,606
Loans Collectively Evaluated for Impairment, Allowance	12,393	13,820
Commercial Real Estate: Farmland & Commercial
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	10,746	13,806
Loans Individually Evaluated for Impairment, Allowance	546	202
Loans Collectively Evaluated for Impairment, Recorded Investment	1,993,117	1,981,643
Loans Collectively Evaluated for Impairment, Allowance	16,702	19,567
Commercial Real Estate: Multifamily
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	571	777
Loans Individually Evaluated for Impairment, Allowance		200
Loans Collectively Evaluated for Impairment, Recorded Investment	117,708	138,671
Loans Collectively Evaluated for Impairment, Allowance	790	1,048
Residential First Lien
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	6,752	5,699
Loans Collectively Evaluated for Impairment, Recorded Investment	410,930	404,545
Loans Collectively Evaluated for Impairment, Allowance	2,387	3,509
Residential Junior Lien
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	1,008	950
Loans Collectively Evaluated for Impairment, Recorded Investment	594,831	551,388
Loans Collectively Evaluated for Impairment, Allowance	3,695	5,321
Consumer
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	1,230	1,297
Loans Collectively Evaluated for Impairment, Recorded Investment	54,766	56,447
Loans Collectively Evaluated for Impairment, Allowance	517	638
Foreign
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	752	752
Loans Collectively Evaluated for Impairment, Recorded Investment	169,356	178,261
Loans Collectively Evaluated for Impairment, Allowance	$ 934	$ 1,152

X

- Definition

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953423-111524

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- Definition

Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953423-111524

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (h)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953423-111524

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+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (h)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953423-111524

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