Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI (6) (Details) (USD $)	3 Months Ended
	Mar. 31, 2015 Scale Factor Market Loan	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	$ 69,616,000
Provision for loan losses, LHFI	1,785,000			(805,000)
Balance at end of period	71,321,000
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Total	71,321,000
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
Length of loss emergence period in the quantitative portion of the allowance for loan loss methodology for commercial LHFI	1 year 6 months
Additional provision amount quantitative portion of the allowance for loan loss methodology for commercial LHFI	2,300,000
Minimum score for qualitative risk factor	0
Maximum score for qualitative risk factor	100
Amount of provision recapture resulting from the elimination of cap and floors for criticized risk ratings in the qualitative portion of the allowance for loan loss methodology for commercial LHFI	1,800,000
Amount of provision recapture resulting from market region distribution related to qualitative portion of the allowance for loan loss methodology for commercial LHFI	2,000,000
Amount of provision recapture resulting from market region distribution related to quantitative portion of the allowance for loan loss methodology for commercial LHFI	905,000
Additional provision due to revision of methodology	1,100,000	822,000	1,400,000
Maximum value of commercial LHFI which were subject to further refinement of allowance for loan loss methodology		500,000
Allowance for Loan Loses, LHFI [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	69,616,000			66,448,000
Loans charged-off	(3,004,000)			(3,016,000)
Recoveries	2,924,000			4,891,000
Net (charge-offs) recoveries	(80,000)			1,875,000
Provision for loan losses, LHFI	1,785,000			(805,000)
Balance at end of period	71,321,000			67,518,000
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually	14,016,000			5,541,000
Collectively	57,305,000			61,977,000
Total	71,321,000			67,518,000
Loans Secured by Real Estate [Member] | Construction Land Development and Other Land [Member] | Allowance for Loan Loses, LHFI [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	13,073,000			13,165,000
Loans charged-off	(9,000)			(49,000)
Recoveries	240,000			2,615,000
Provision for loan losses, LHFI	2,969,000			(3,297,000)
Balance at end of period	16,273,000			12,434,000
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually	4,097,000			674,000
Collectively	12,176,000			11,760,000
Total	16,273,000			12,434,000
Loans Secured by Real Estate [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	9,677,000			9,633,000
Loans charged-off	(434,000)			(1,282,000)
Recoveries	43,000			64,000
Provision for loan losses, LHFI	(402,000)			515,000
Balance at end of period	8,884,000			8,930,000
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually	429,000			244,000
Collectively	8,455,000			8,686,000
Total	8,884,000			8,930,000
Loans Secured by Real Estate [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	18,523,000			19,672,000
Loans charged-off	0			(47,000)
Recoveries	315,000			33,000
Provision for loan losses, LHFI	15,000			(859,000)
Balance at end of period	18,853,000			18,799,000
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually	2,728,000			2,123,000
Collectively	16,125,000			16,676,000
Total	18,853,000			18,799,000
Loans Secured by Real Estate [Member] | Other Real Estate Secured [Member] | Allowance for Loan Loses, LHFI [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	2,141,000			2,080,000
Loans charged-off	(24,000)			0
Recoveries	3,000			0
Provision for loan losses, LHFI	(42,000)			24,000
Balance at end of period	2,078,000			2,104,000
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually	51,000			121,000
Collectively	2,027,000			1,983,000
Total	2,078,000			2,104,000
Commercial and Industrial Loans [Member] | Allowance for Loan Loses, LHFI [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	19,917,000			15,522,000
Loans charged-off	(669,000)			(121,000)
Recoveries	342,000			185,000
Provision for loan losses, LHFI	487,000			3,494,000
Balance at end of period	20,077,000			19,080,000
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually	6,502,000			2,111,000
Collectively	13,575,000			16,969,000
Total	20,077,000			19,080,000
Consumer Loans [Member] | Allowance for Loan Loses, LHFI [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	2,149,000			2,405,000
Loans charged-off	(498,000)			(510,000)
Recoveries	937,000			1,068,000
Provision for loan losses, LHFI	(627,000)			(910,000)
Balance at end of period	1,961,000			2,053,000
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually	0			1,000
Collectively	1,961,000			2,052,000
Total	1,961,000			2,053,000
State and Other Political Subdivision Loans [Member] | Allowance for Loan Loses, LHFI [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	1,314,000			1,205,000
Loans charged-off	0			0
Recoveries	0			0
Provision for loan losses, LHFI	(627,000)			261,000
Balance at end of period	687,000			1,466,000
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually	0			0
Collectively	687,000			1,466,000
Total	687,000			1,466,000
Other Loans [Member] | Allowance for Loan Loses, LHFI [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	2,822,000			2,766,000
Loans charged-off	(1,370,000)			(1,007,000)
Recoveries	1,044,000			926,000
Provision for loan losses, LHFI	12,000			(33,000)
Balance at end of period	2,508,000			2,652,000
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually	209,000			267,000
Collectively	2,299,000			2,385,000
Total	$ 2,508,000			$ 2,652,000