Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI (1) (Details) (USD $)	6 Months Ended		12 Months Ended
	Jun. 30, 2013 Region	Jun. 30, 2012	Dec. 31, 2012
Loan and Lease Receivables, Impaired [Abstract]
Unpaid Principal Balance	$ 99,830,000		$ 119,818,000
Total LHFI With No Related Allowance Recorded	25,316,000		23,190,000
Total LHFI With an Allowance Recorded	49,002,000		59,173,000
Total Carrying Amount	74,318,000		82,363,000
Related Allowance	10,690,000		10,504,000
Average Recorded Investment	78,340,000		96,410,000
Maximum concentration of loan as a percentage of total LHFI (in hundredths)	10.00%
Key market regions	5
Carrying amounts of nonaccrual LHFI considered for impairment analysis	74,300,000		82,400,000
Minimum loan amount for loan to be individually assessed for impairment	500,000
Nonaccrual financing receivable, specifically evaluated for impairment	29,800,000		40,600,000
Nonaccrual financing receivable, allowance for credit losses, specifically evaluated for impairment	2,200,000		5,900,000
Nonaccrual financing receivable, allowance for credit losses, charge-offs, specifically evaluated for impairment	1,600,000	6,400,000
Nonaccrual financing receivable specifically evaluated for impairment allowance for credit losses provisions	2,700,000	1,900,000
Nonaccrual financing receivable, not specifically evaluated for impairment	44,500,000		41,800,000
Nonaccrual financing receivable, allowance for credit losses, not specifically evaluated for impairment	8,500,000		4,600,000
Classified as Troubled Debt Restructuring LHFI	19,300,000		24,300,000
TDRs comprised of credits with interest only payments	15,000,000		21,600,000
Financing receivable, related allowance	2,200,000		4,300,000
Financing receivable, related charge-offs	429,000	1,100,000
Loans Secured by Real Estate [Member] | Construction Land Development And Other Financing Receivable [Member]
Loan and Lease Receivables, Impaired [Abstract]
Unpaid Principal Balance	29,645,000		46,558,000
Total LHFI With No Related Allowance Recorded	10,810,000		9,571,000
Total LHFI With an Allowance Recorded	5,449,000		17,534,000
Total Carrying Amount	16,259,000		27,105,000
Related Allowance	1,527,000		4,992,000
Average Recorded Investment	21,682,000		33,759,000
Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member]
Loan and Lease Receivables, Impaired [Abstract]
Unpaid Principal Balance	29,872,000		35,155,000
Total LHFI With No Related Allowance Recorded	2,208,000		2,533,000
Total LHFI With an Allowance Recorded	21,629,000		24,581,000
Total Carrying Amount	23,837,000		27,114,000
Related Allowance	583,000		1,469,000
Average Recorded Investment	25,476,000		25,731,000
Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member]
Loan and Lease Receivables, Impaired [Abstract]
Unpaid Principal Balance	21,189,000		23,337,000
Total LHFI With No Related Allowance Recorded	9,816,000		8,184,000
Total LHFI With an Allowance Recorded	8,602,000		10,105,000
Total Carrying Amount	18,418,000		18,289,000
Related Allowance	1,936,000		2,296,000
Average Recorded Investment	18,353,000		21,135,000
Loans Secured by Real Estate [Member] | Other Loans Secured by Real Estate [Member]
Loan and Lease Receivables, Impaired [Abstract]
Unpaid Principal Balance	548,000		6,036,000
Total LHFI With No Related Allowance Recorded	0		566,000
Total LHFI With an Allowance Recorded	511,000		3,390,000
Total Carrying Amount	511,000		3,956,000
Related Allowance	38,000		760,000
Average Recorded Investment	2,233,000		4,914,000
Commercial and Industrial Loans [Member]
Loan and Lease Receivables, Impaired [Abstract]
Unpaid Principal Balance	17,141,000		7,251,000
Total LHFI With No Related Allowance Recorded	2,433,000		2,336,000
Total LHFI With an Allowance Recorded	11,760,000		2,405,000
Total Carrying Amount	14,193,000		4,741,000
Related Allowance	6,273,000		640,000
Average Recorded Investment	9,467,000		9,444,000
Consumer Loans [Member]
Loan and Lease Receivables, Impaired [Abstract]
Unpaid Principal Balance	489,000		624,000
Total LHFI With No Related Allowance Recorded	0		0
Total LHFI With an Allowance Recorded	267,000		360,000
Total Carrying Amount	267,000		360,000
Related Allowance	2,000		5,000
Average Recorded Investment	314,000		592,000
Other Loans [Member]
Loan and Lease Receivables, Impaired [Abstract]
Unpaid Principal Balance	946,000		857,000
Total LHFI With No Related Allowance Recorded	49,000		0
Total LHFI With an Allowance Recorded	784,000		798,000
Total Carrying Amount	833,000		798,000
Related Allowance	331,000		342,000
Average Recorded Investment	$ 815,000		$ 835,000