Allowance for Probable Loan Losses (By Loan Class) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Allowance for probable loan losses
Balance at the beginning of the period	$ 61,784	$ 66,251	$ 66,988	$ 64,828
Losses charged to allowance	(7,535)	(14,342)	(27,110)	(17,029)
Recoveries credited to allowance	687	862	5,924	2,595
Net (losses) recoveries charged to allowance	(6,848)	(13,480)	(21,186)	(14,434)
Provision charged to operations	7,097	7,767	16,231	10,144
Balance at the end of the period	62,033	60,538	62,033	60,538
Watch - List Impaired
Allowance for probable loan losses
Losses charged to allowance			(16,800)
Commercial
Allowance for probable loan losses
Balance at the beginning of the period	25,783	23,519	21,431	22,352
Losses charged to allowance	(5,396)	(13,073)	(24,467)	(15,382)
Recoveries credited to allowance	513	534	5,656	1,330
Net (losses) recoveries charged to allowance	(4,883)	(12,539)	(18,811)	(14,052)
Provision charged to operations	5,082	7,922	23,362	10,602
Balance at the end of the period	25,982	18,902	25,982	18,902
Commercial Real Estate: Other Construction and Land Development
Allowance for probable loan losses
Balance at the beginning of the period	10,870	14,369	13,920	12,955
Losses charged to allowance	(2)	(685)	(2)	(685)
Recoveries credited to allowance	3	38	7	39
Net (losses) recoveries charged to allowance	1	(647)	5	(646)
Provision charged to operations	238	(198)	(2,816)	1,215
Balance at the end of the period	11,109	13,524	11,109	13,524
Commercial Real Estate: Farmland & Commercial
Allowance for probable loan losses
Balance at the beginning of the period	16,974	17,976	19,769	18,683
Losses charged to allowance	(1,843)	(339)	(1,890)	(356)
Recoveries credited to allowance	75	7	86	813
Net (losses) recoveries charged to allowance	(1,768)	(332)	(1,804)	457
Provision charged to operations	1,736	241	(1,023)	(1,255)
Balance at the end of the period	16,942	17,885	16,942	17,885
Commercial Real Estate: Multifamily
Allowance for probable loan losses
Balance at the beginning of the period	910	840	1,248	846
Losses charged to allowance			(180)
Net (losses) recoveries charged to allowance			(180)
Provision charged to operations	(55)	(155)	(213)	(161)
Balance at the end of the period	855	685	855	685
Residential First Lien
Allowance for probable loan losses
Balance at the beginning of the period	2,369	3,573	3,509	3,589
Losses charged to allowance	(23)	(1)	(30)	(91)
Recoveries credited to allowance	4	10	7	24
Net (losses) recoveries charged to allowance	(19)	9	(23)	(67)
Provision charged to operations	(73)	(148)	(1,209)	(88)
Balance at the end of the period	2,277	3,434	2,277	3,434
Residential Junior Lien
Allowance for probable loan losses
Balance at the beginning of the period	3,420	4,261	5,321	4,683
Losses charged to allowance	(155)	(5)	(324)	(102)
Recoveries credited to allowance	76	145	114	251
Net (losses) recoveries charged to allowance	(79)	140	(210)	149
Provision charged to operations	59	(93)	(1,711)	(524)
Balance at the end of the period	3,400	4,308	3,400	4,308
Consumer
Allowance for probable loan losses
Balance at the beginning of the period	530	644	638	660
Losses charged to allowance	(116)	(239)	(217)	(413)
Recoveries credited to allowance	5	124	42	130
Net (losses) recoveries charged to allowance	(111)	(115)	(175)	(283)
Provision charged to operations	113	96	69	248
Balance at the end of the period	532	625	532	625
Foreign
Allowance for probable loan losses
Balance at the beginning of the period	928	1,069	1,152	1,060
Recoveries credited to allowance	11	4	12	8
Net (losses) recoveries charged to allowance	11	4	12	8
Provision charged to operations	(3)	102	(228)	107
Balance at the end of the period	$ 936	$ 1,175	$ 936	$ 1,175

Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

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Amount, after recoveries, of loans and leases that have been written-off.

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- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for 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 50
-Paragraph 11B
-Subparagraph (g)
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(d))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 6
-Section L
-Subsection 1

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Amount of expense related to estimated loss from loan and lease transactions.

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-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
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