Loans (Details 14) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment	$ 26,699	$ 50,698
Impaired loans with no related allowance recorded, Unpaid Principal Balance	59,680	97,793
Impaired loans with an allowance recorded, Recorded investment	25,273	33,271
Impaired loans with an allowance recorded, Unpaid Principal Balance	27,960	35,262
Impaired loans with an allowance recorded, Related allowance	3,295	6,505
Recorded investment	51,972	83,969
Unpaid principal balance	87,640	133,055
Loans gross [Member]
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment	19,761	36,520
Impaired loans with no related allowance recorded, Unpaid Principal Balance	44,005	67,163
Impaired loans with an allowance recorded, Recorded investment	25,273	33,271
Impaired loans with an allowance recorded, Unpaid Principal Balance	27,960	35,262
Impaired loans with an allowance recorded, Related allowance	3,295	6,505
Recorded investment	45,034	69,791
Unpaid principal balance	71,965	102,425
Other Loans Held For Sale [Member]
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment	6,938	14,178
Impaired loans with no related allowance recorded, Unpaid Principal Balance	15,675	30,630
Recorded investment	6,938	14,178
Unpaid principal balance	15,675	30,630
Construction, land development, and other land loans [Member]
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment	11,866	21,386
Impaired loans with no related allowance recorded, Unpaid Principal Balance	35,773	53,534
Impaired loans with an allowance recorded, Recorded investment	5,385	9,702
Impaired loans with an allowance recorded, Unpaid Principal Balance	5,835	11,624
Impaired loans with an allowance recorded, Related allowance	321	3,301
Recorded investment	17,701	31,088
Unpaid principal balance	41,608	65,158
Construction, land development, and other land loans [Member] | Loans gross [Member]
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment	9,753	16,845
Impaired loans with no related allowance recorded, Unpaid Principal Balance	26,701	36,735
Impaired loans with an allowance recorded, Recorded investment	5,835	9,702
Impaired loans with an allowance recorded, Unpaid Principal Balance	5,835	11,624
Impaired loans with an allowance recorded, Related allowance	321	3,301
Recorded investment	15,588	26,547
Unpaid principal balance	32,536	48,359
Construction, land development, and other land loans [Member] | Other Loans Held For Sale [Member]
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment	2,113	4,541
Impaired loans with no related allowance recorded, Unpaid Principal Balance	9,072	16,799
Recorded investment	2,113	4,541
Unpaid principal balance	9,072	16,799
Multifamily residential [Member]
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment
Impaired loans with no related allowance recorded, Unpaid Principal Balance
Impaired loans with an allowance recorded, Recorded investment	245	247
Impaired loans with an allowance recorded, Unpaid Principal Balance	245	247
Impaired loans with an allowance recorded, Related allowance	7	9
Recorded investment	245	247
Unpaid principal balance	245	247
Multifamily residential [Member] | Loans gross [Member]
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment
Impaired loans with no related allowance recorded, Unpaid Principal Balance
Impaired loans with an allowance recorded, Recorded investment	245	247
Impaired loans with an allowance recorded, Unpaid Principal Balance	245	247
Impaired loans with an allowance recorded, Related allowance	7	9
Recorded investment	245	247
Unpaid principal balance	245	247
Multifamily residential [Member] | Other Loans Held For Sale [Member]
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment
Impaired loans with no related allowance recorded, Unpaid Principal Balance
Recorded investment
Unpaid principal balance
Nonfarm nonresidential [Member]
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment	13,088	25,684
Impaired loans with no related allowance recorded, Unpaid Principal Balance	19,294	36,019
Impaired loans with an allowance recorded, Recorded investment	16,203	20,784
Impaired loans with an allowance recorded, Unpaid Principal Balance	16,583	20,784
Impaired loans with an allowance recorded, Related allowance	2,759	2,886
Recorded investment	29,291	46,468
Unpaid principal balance	35,877	56,803
Nonfarm nonresidential [Member] | Loans gross [Member]
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment	8,263	16,047
Impaired loans with no related allowance recorded, Unpaid Principal Balance	12,691	22,188
Impaired loans with an allowance recorded, Recorded investment	16,203	20,784
Impaired loans with an allowance recorded, Unpaid Principal Balance	16,583	20,784
Impaired loans with an allowance recorded, Related allowance	2,759	2,886
Recorded investment	24,466	36,831
Unpaid principal balance	29,274	42,972
Nonfarm nonresidential [Member] | Other Loans Held For Sale [Member]
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment	4,825	9,637
Impaired loans with no related allowance recorded, Unpaid Principal Balance	6,603	13,831
Recorded investment	4,825	9,637
Unpaid principal balance	6,603	13,831
Total Commercial real estate [Member]
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment	24,954	47,070
Impaired loans with no related allowance recorded, Unpaid Principal Balance	55,067	89,553
Impaired loans with an allowance recorded, Recorded investment	22,283	30,733
Impaired loans with an allowance recorded, Unpaid Principal Balance	22,663	32,655
Impaired loans with an allowance recorded, Related allowance	3,087	6,196
Recorded investment	47,237	77,803
Unpaid principal balance	77,730	122,208
Total Commercial real estate [Member] | Loans gross [Member]
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment	18,016	32,892
Impaired loans with no related allowance recorded, Unpaid Principal Balance	39,392	58,923
Impaired loans with an allowance recorded, Recorded investment	22,283	30,733
Impaired loans with an allowance recorded, Unpaid Principal Balance	22,663	32,655
Impaired loans with an allowance recorded, Related allowance	3,087	6,196
Recorded investment	40,299	63,625
Unpaid principal balance	62,055	91,578
Total Commercial real estate [Member] | Other Loans Held For Sale [Member]
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment	6,938	14,178
Impaired loans with no related allowance recorded, Unpaid Principal Balance	15,675	30,630
Recorded investment	6,938	14,178
Unpaid principal balance	15,675	30,630
Single Family Residential Revolving Open End Loans [Member]
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment
Impaired loans with no related allowance recorded, Unpaid Principal Balance
Impaired loans with an allowance recorded, Recorded investment
Impaired loans with an allowance recorded, Unpaid Principal Balance
Impaired loans with an allowance recorded, Related allowance
Recorded investment
Unpaid principal balance
Single Family Residential Revolving Open End Loans [Member] | Loans gross [Member]
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment
Impaired loans with no related allowance recorded, Unpaid Principal Balance
Impaired loans with an allowance recorded, Recorded investment
Impaired loans with an allowance recorded, Unpaid Principal Balance
Impaired loans with an allowance recorded, Related allowance
Recorded investment
Unpaid principal balance
Single Family Residential Revolving Open End Loans [Member] | Other Loans Held For Sale [Member]
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment
Impaired loans with no related allowance recorded, Unpaid Principal Balance
Recorded investment
Unpaid principal balance
Single Family Residential Closed End First Lien [Member]
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment	982	2,742
Impaired loans with no related allowance recorded, Unpaid Principal Balance	3,407	6,928
Impaired loans with an allowance recorded, Recorded investment	2,033	1,689
Impaired loans with an allowance recorded, Unpaid Principal Balance	4,340	1,689
Impaired loans with an allowance recorded, Related allowance	108	161
Recorded investment	3,015	4,431
Unpaid principal balance	7,747	8,617
Single Family Residential Closed End First Lien [Member] | Loans gross [Member]
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment	982	2,742
Impaired loans with no related allowance recorded, Unpaid Principal Balance	3,407	6,928
Impaired loans with an allowance recorded, Recorded investment	2,033	1,689
Impaired loans with an allowance recorded, Unpaid Principal Balance	4,340	1,689
Impaired loans with an allowance recorded, Related allowance	108	161
Recorded investment	3,015	4,431
Unpaid principal balance	7,747	8,617
Single Family Residential Closed End First Lien [Member] | Other Loans Held For Sale [Member]
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment
Impaired loans with no related allowance recorded, Unpaid Principal Balance
Recorded investment
Unpaid principal balance
Single Family Residential Closed End Junior Lien [Member]
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment	10
Impaired loans with no related allowance recorded, Unpaid Principal Balance	27
Impaired loans with an allowance recorded, Recorded investment	151	183
Impaired loans with an allowance recorded, Unpaid Principal Balance	151	183
Impaired loans with an allowance recorded, Related allowance	50	54
Recorded investment	161	183
Unpaid principal balance	178	183
Single Family Residential Closed End Junior Lien [Member] | Loans gross [Member]
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment	10
Impaired loans with no related allowance recorded, Unpaid Principal Balance	27
Impaired loans with an allowance recorded, Recorded investment	151	183
Impaired loans with an allowance recorded, Unpaid Principal Balance	151	183
Impaired loans with an allowance recorded, Related allowance	50	54
Recorded investment	161	183
Unpaid principal balance	178	183
Single Family Residential Closed End Junior Lien [Member] | Other Loans Held For Sale [Member]
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment
Impaired loans with no related allowance recorded, Unpaid Principal Balance
Recorded investment
Unpaid principal balance
Total Single Family Residential Loans [Member]
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment	992	2,742
Impaired loans with no related allowance recorded, Unpaid Principal Balance	3,434	6,928
Impaired loans with an allowance recorded, Recorded investment	2,184	1,872
Impaired loans with an allowance recorded, Unpaid Principal Balance	4,491	1,872
Impaired loans with an allowance recorded, Related allowance	158	215
Recorded investment	3,176	4,614
Unpaid principal balance	7,925	8,800
Total Single Family Residential Loans [Member] | Loans gross [Member]
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment	992	2,742
Impaired loans with no related allowance recorded, Unpaid Principal Balance	3,434	6,928
Impaired loans with an allowance recorded, Recorded investment	2,184	1,872
Impaired loans with an allowance recorded, Unpaid Principal Balance	4,491	1,872
Impaired loans with an allowance recorded, Related allowance	158	215
Recorded investment	3,176	4,614
Unpaid principal balance	7,925	8,800
Total Single Family Residential Loans [Member] | Other Loans Held For Sale [Member]
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment
Impaired loans with no related allowance recorded, Unpaid Principal Balance
Recorded investment
Unpaid principal balance
Commercial and Industrial [Member]
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment	753	886
Impaired loans with no related allowance recorded, Unpaid Principal Balance	1,179	1,312
Impaired loans with an allowance recorded, Recorded investment	765	622
Impaired loans with an allowance recorded, Unpaid Principal Balance	765	691
Impaired loans with an allowance recorded, Related allowance	45	88
Recorded investment	1,518	1,508
Unpaid principal balance	1,944	2,003
Commercial and Industrial [Member] | Loans gross [Member]
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment	753	886
Impaired loans with no related allowance recorded, Unpaid Principal Balance	1,179	1,312
Impaired loans with an allowance recorded, Recorded investment	765	622
Impaired loans with an allowance recorded, Unpaid Principal Balance	765	691
Impaired loans with an allowance recorded, Related allowance	45	88
Recorded investment	1,518	1,508
Unpaid principal balance	1,944	2,003
Commercial and Industrial [Member] | Other Loans Held For Sale [Member]
Summary of composition of impaired loans by class
Impaired loans with no related allowance recorded, Recorded investment
Impaired loans with no related allowance recorded, Unpaid Principal Balance
Recorded investment
Unpaid principal balance
Consumer-other [Member]
Summary of composition of impaired loans by class
Impaired loans with an allowance recorded, Recorded investment	41	44
Impaired loans with an allowance recorded, Unpaid Principal Balance	41	44
Impaired loans with an allowance recorded, Related allowance	5	6
Recorded investment	41	44
Unpaid principal balance	41	44
Consumer-other [Member] | Loans gross [Member]
Summary of composition of impaired loans by class
Impaired loans with an allowance recorded, Recorded investment	41	44
Impaired loans with an allowance recorded, Unpaid Principal Balance	41	44
Impaired loans with an allowance recorded, Related allowance	5	6
Recorded investment	41	44
Unpaid principal balance	41	44
Consumer-other [Member] | Other Loans Held For Sale [Member]
Summary of composition of impaired loans by class
Recorded investment
Unpaid principal balance