Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Loan Portfolio [Abstract]
Total Loans held for investment (LHFI)	$ 5,474,396	$ 5,592,754
Less Allowance For Loan Losses, LHFI	76,900	78,738
Net LHFI	5,397,496	5,514,016
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	83,322	82,363
LHFI, Collectively Evaluated For Impairment	5,391,074	5,510,391
Total LHFI	5,474,396	5,592,754
Loans Secured by Real Estate [Member] \| Construction Land Development and Other Land Loans [Member]
Loan Portfolio [Abstract]
Total Loans held for investment (LHFI)	485,419	468,975
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	24,443	27,105
LHFI, Collectively Evaluated For Impairment	460,976	441,870
Total LHFI	485,419	468,975
Loans Secured by Real Estate [Member] \| Secured by 1-4 Family Residential Properties [Member]
Loan Portfolio [Abstract]
Total Loans held for investment (LHFI)	1,372,901	1,497,480
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	27,149	27,114
LHFI, Collectively Evaluated For Impairment	1,345,752	1,470,366
Total LHFI	1,372,901	1,497,480
Loans Secured by Real Estate [Member] \| Secured by Nonfarm, Nonresidential Properties [Member]
Loan Portfolio [Abstract]
Total Loans held for investment (LHFI)	1,385,669	1,410,264
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	17,880	18,289
LHFI, Collectively Evaluated For Impairment	1,367,789	1,391,975
Total LHFI	1,385,669	1,410,264
Loans Secured by Real Estate [Member] \| Other Real Estate Properties [Member]
Loan Portfolio [Abstract]
Total Loans held for investment (LHFI)	174,680	189,949
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	1,040	3,956
LHFI, Collectively Evaluated For Impairment	173,640	185,993
Total LHFI	174,680	189,949
Commercial and Industrial Loans [Member]
Loan Portfolio [Abstract]
Total Loans held for investment (LHFI)	1,206,851	1,169,513
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	9,053	4,741
LHFI, Collectively Evaluated For Impairment	1,197,798	1,164,772
Total LHFI	1,206,851	1,169,513
Consumer Loans [Member]
Loan Portfolio [Abstract]
Total Loans held for investment (LHFI)	160,253	171,660
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	277	360
LHFI, Collectively Evaluated For Impairment	159,976	171,300
Total LHFI	160,253	171,660
Other Loans [Member]
Loan Portfolio [Abstract]
Total Loans held for investment (LHFI)	688,623	684,913
Loans and Leases Receivable, Other Information [Abstract]
LHFI, Individually Evaluated For Impairment	3,480	798
LHFI, Collectively Evaluated For Impairment	685,143	684,115
Total LHFI	$ 688,623	$ 684,913

The allowance for loan and lease losses represents the reserve to cover probable credit losses related to specifically identified loans and leases, as well as probable credit losses inherent in the remainder of the loan portfolio as of the balance sheet date. For banks, include currently required allocated transfer risk reserves. Include carryover of or adjustments to the allowance for loan losses in connection with business combinations determined to be appropriate.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher OTS

-Name Federal Regulation (FR)

-Number Title 12

-Chapter V

-Section 563c.102

-Paragraph 8

-Subparagraph a(ii)

-Subsection I

-LegacyDoc This is a non-GAAP reference that was included in the 2009 taxonomy. It will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 6

-Section L

-Subsection 1

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 114

-Paragraph 20

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-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

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 9

-Section 03

-Paragraph 7

-Subparagraph d

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 8, 9

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (b)(1)(ii)

-URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544

+ Details

- Definition

Reflects the aggregate gross carrying amount of all categories of loans and leases held in portfolio, after deducting deferred income, but before deducting the allowance for losses on loans and leases.

+ References+ Details