Allowance for Probable Loan Losses (By Loan Class) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2016	Mar. 31, 2015
Allowance for probable loan losses
Balance at the beginning of the period	$ 66,988	$ 64,828
Losses charged to allowance	(19,575)	(2,687)
Recoveries credited to allowance	5,237	1,733
Net (losses) recoveries charged to allowance	(14,338)	(954)
Provision charged to operations	9,134	2,377
Balance at the end of the period	61,784	66,251
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	21,431	22,352
Losses charged to allowance	(19,071)	(2,309)
Recoveries credited to allowance	5,143	796
Net (losses) recoveries charged to allowance	(13,928)	(1,513)
Provision charged to operations	18,280	2,680
Balance at the end of the period	25,783	23,519
Commercial Real Estate: Other Construction and Land Development
Allowance for probable loan losses
Balance at the beginning of the period	13,920	12,955
Recoveries credited to allowance	4	1
Net (losses) recoveries charged to allowance	4	1
Provision charged to operations	(3,054)	1,413
Balance at the end of the period	10,870	14,369
Commercial Real Estate: Farmland & Commercial
Allowance for probable loan losses
Balance at the beginning of the period	19,769	18,683
Losses charged to allowance	(47)	(17)
Recoveries credited to allowance	11	806
Net (losses) recoveries charged to allowance	(36)	789
Provision charged to operations	(2,759)	(1,496)
Balance at the end of the period	16,974	17,976
Commercial Real Estate: Multifamily
Allowance for probable loan losses
Balance at the beginning of the period	1,248	846
Losses charged to allowance	(180)
Net (losses) recoveries charged to allowance	(180)
Provision charged to operations	(158)	(6)
Balance at the end of the period	910	840
Residential First Lien
Allowance for probable loan losses
Balance at the beginning of the period	3,509	3,589
Losses charged to allowance	(7)	(90)
Recoveries credited to allowance	3	14
Net (losses) recoveries charged to allowance	(4)	(76)
Provision charged to operations	(1,136)	60
Balance at the end of the period	2,369	3,573
Residential Junior Lien
Allowance for probable loan losses
Balance at the beginning of the period	5,321	4,683
Losses charged to allowance	(169)	(97)
Recoveries credited to allowance	38	106
Net (losses) recoveries charged to allowance	(131)	9
Provision charged to operations	(1,770)	(431)
Balance at the end of the period	3,420	4,261
Consumer
Allowance for probable loan losses
Balance at the beginning of the period	638	660
Losses charged to allowance	(101)	(174)
Recoveries credited to allowance	37	6
Net (losses) recoveries charged to allowance	(64)	(168)
Provision charged to operations	(44)	152
Balance at the end of the period	530	644
Foreign
Allowance for probable loan losses
Balance at the beginning of the period	1,152	1,060
Recoveries credited to allowance	1	4
Net (losses) recoveries charged to allowance	1	4
Provision charged to operations	(225)	5
Balance at the end of the period	$ 928	$ 1,069

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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- Definition

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

+ References

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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)
-URI http://asc.fasb.org/extlink&oid=49124121&loc=SL6953423-111524

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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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Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 6
-Section L
-Subsection 1

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- Definition

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

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
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-Subparagraph (SX 210.9-04.11)
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