Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI (6) (Details) (USD $)	3 Months Ended
	Mar. 31, 2013 Scale Loan Factor Region	Mar. 31, 2012
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	$ 78,738,000
Provision for loan losses, LHFI	(2,968,000)	3,293,000
Balance at end of period	76,900,000
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Total	76,900,000
Number of loan types for commercial portfolio	9
Number of unique qualitative factors used to analyze consumer loans	5
Number of risk rate factors for commercial loans	450
Minimum score for qualitative risk factor	0
Maximum score for qualitative risk factor	100
One time additional provision due to revision of methodology	1,400,000
Allowance for Loan Loses, LHFI [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	78,738,000	89,518,000
Loans charged-off	(3,325,000)	(5,376,000)
Recoveries	4,455,000	3,444,000
Net recoveries (charge-offs)	1,130,000	(1,932,000)
Provision for loan losses, LHFI	(2,968,000)	3,293,000
Balance at end of period	76,900,000	90,879,000
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually	11,013,000	14,888,000
Collectively	65,887,000	75,991,000
Total	76,900,000	90,879,000
Real Estate Secured Financing Receivable [Member] | Construction Land Development and Other Land Loans [Member] | Allowance for Loan Loses, LHFI [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	21,838,000	27,220,000
Loans charged-off	(297,000)	(1,526,000)
Recoveries	0	0
Provision for loan losses, LHFI	(1,964,000)	21,000
Balance at end of period	19,577,000	25,715,000
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually	3,514,000	5,963,000
Collectively	16,063,000	19,752,000
Total	19,577,000	25,715,000
Real Estate Secured Financing Receivable [Member] | Secured by 1-4 Family Residential Properties [Member] | Allowance for Loan Loses, LHFI [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	12,957,000	12,650,000
Loans charged-off	(209,000)	(716,000)
Recoveries	59,000	208,000
Provision for loan losses, LHFI	(1,083,000)	598,000
Balance at end of period	11,724,000	12,740,000
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually	1,117,000	1,240,000
Collectively	10,607,000	11,500,000
Total	11,724,000	12,740,000
Real Estate Secured Financing Receivable [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Allowance for Loan Loses, LHFI [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	21,096,000	24,358,000
Loans charged-off	(168,000)	(127,000)
Recoveries	0	0
Provision for loan losses, LHFI	(896,000)	3,653,000
Balance at end of period	20,032,000	27,884,000
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually	2,170,000	5,443,000
Collectively	17,862,000	22,441,000
Total	20,032,000	27,884,000
Real Estate Secured Financing Receivable [Member] | Other Loans Secured by Real Estate [Member] | Allowance for Loan Loses, LHFI [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	2,197,000	3,079,000
Loans charged-off	(910,000)	(234,000)
Recoveries	0	0
Provision for loan losses, LHFI	53,000	176,000
Balance at end of period	1,340,000	3,021,000
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually	32,000	1,002,000
Collectively	1,308,000	2,019,000
Total	1,340,000	3,021,000
Commercial And Industrial Loans [Member] | Allowance for Loan Loses, LHFI [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	14,319,000	15,868,000
Loans charged-off	(40,000)	(331,000)
Recoveries	2,031,000	821,000
Provision for loan losses, LHFI	1,360,000	(320,000)
Balance at end of period	17,670,000	16,038,000
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually	3,584,000	1,168,000
Collectively	14,086,000	14,870,000
Total	17,670,000	16,038,000
Consumer Loans [Member] | Allowance for Loan Loses, LHFI [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	3,087,000	3,656,000
Loans charged-off	(634,000)	(1,038,000)
Recoveries	1,451,000	1,352,000
Provision for loan losses, LHFI	(876,000)	(766,000)
Balance at end of period	3,028,000	3,204,000
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually	2,000	7,000
Collectively	3,026,000	3,197,000
Total	3,028,000	3,204,000
Other Loans [Member] | Allowance for Loan Loses, LHFI [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	3,244,000	2,687,000
Loans charged-off	(1,067,000)	(1,404,000)
Recoveries	914,000	1,063,000
Provision for loan losses, LHFI	438,000	(69,000)
Balance at end of period	3,529,000	2,277,000
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually	594,000	65,000
Collectively	2,935,000	2,212,000
Total	$ 3,529,000	$ 2,277,000