Aging of Past Due Loans by Loan Class (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	$ 10,400	$ 12,307
60 - 89 Days Past Due	4,097	2,802
90+ Days Past Due	9,629	11,961
Total Past Due	24,126	27,070
Current Loans	1,665,290	1,683,651
Total loans	1,689,416	1,710,721
Non Covered Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	8,955	10,929
60 - 89 Days Past Due	3,576	2,552
90+ Days Past Due	7,677	9,112
Total Past Due	20,208	22,593
Current Loans	1,546,968	1,536,446
Total loans	1,567,176	1,559,039
Non Covered Loans \| Commercial Loans \| Construction Development And Other Land
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	39	118
60 - 89 Days Past Due	46	10
90+ Days Past Due		532
Total Past Due	85	660
Current Loans	41,186	34,595
Total loans	41,271	35,255
Non Covered Loans \| Commercial Loans \| Commercial and Industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	285	93
60 - 89 Days Past Due	6	39
90+ Days Past Due	103	2,631
Total Past Due	394	2,763
Current Loans	82,705	92,692
Total loans	83,099	95,455
Non Covered Loans \| Commercial Loans \| Multi-family Residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	81	115
60 - 89 Days Past Due	110
Total Past Due	191	115
Current Loans	97,289	70,082
Total loans	97,480	70,197
Non Covered Loans \| Commercial Loans \| Single-family Non-owner Occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	914	611
60 - 89 Days Past Due	513	554
90+ Days Past Due	425	1,203
Total Past Due	1,852	2,368
Current Loans	133,319	133,191
Total loans	135,171	135,559
Non Covered Loans \| Commercial Loans \| Non-farm, Non-residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	1,075	1,014
60 - 89 Days Past Due	783	318
90+ Days Past Due	1,984	1,770
Total Past Due	3,842	3,102
Current Loans	470,064	472,809
Total loans	473,906	475,911
Non Covered Loans \| Commercial Loans \| Agricultural
Financing Receivable, Recorded Investment, Past Due [Line Items]
90+ Days Past Due	4
Total Past Due	4
Current Loans	1,595	2,324
Total loans	1,599	2,324
Non Covered Loans \| Commercial Loans \| Farmland Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	89	245
Total Past Due	89	245
Current Loans	29,428	32,369
Total loans	29,517	32,614
Non Covered Loans \| Consumer Real Estate \| Home Equity Lines
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	492	289
60 - 89 Days Past Due	103	317
90+ Days Past Due	571	442
Total Past Due	1,166	1,048
Current Loans	109,791	110,722
Total loans	110,957	111,770
Non Covered Loans \| Consumer Real Estate \| Single Family Owner Occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	5,436	7,428
60 - 89 Days Past Due	1,931	1,228
90+ Days Past Due	4,564	145
Total Past Due	11,931	8,801
Current Loans	473,544	487,211
Total loans	485,475	496,012
Non Covered Loans \| Consumer Real Estate \| Owner occupied construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due		205
90+ Days Past Due		2,284
Total Past Due		2,489
Current Loans	32,799	26,214
Total loans	32,799	28,703
Non Covered Loans \| Consumer and Other \| Consumer Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	544	811
60 - 89 Days Past Due	84	86
90+ Days Past Due	26	105
Total Past Due	654	1,002
Current Loans	68,693	70,311
Total loans	69,347	71,313
Non Covered Loans \| Consumer and Other \| Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	6,555	3,926
Total loans	6,555	3,926
Covered Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	1,445	1,378
60 - 89 Days Past Due	521	250
90+ Days Past Due	1,952	2,849
Total Past Due	3,918	4,477
Current Loans	118,322	147,205
Total loans	122,240	151,682
Covered Loans \| Commercial Loans \| Construction Development And Other Land
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	120	479
60 - 89 Days Past Due	17
90+ Days Past Due		453
Total Past Due	137	932
Current Loans	12,963	14,933
Total loans	13,100	15,865
Covered Loans \| Commercial Loans \| Commercial and Industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	84	5
60 - 89 Days Past Due	12	44
90+ Days Past Due	34	92
Total Past Due	130	141
Current Loans	2,532	3,184
Total loans	2,662	3,325
Covered Loans \| Commercial Loans \| Multi-family Residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	1,584	1,933
Total loans	1,584	1,933
Covered Loans \| Commercial Loans \| Single-family Non-owner Occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	122
90+ Days Past Due	77	184
Total Past Due	199	184
Current Loans	5,719	7,265
Total loans	5,918	7,449
Covered Loans \| Commercial Loans \| Non-farm, Non-residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	124	209
60 - 89 Days Past Due	140
90+ Days Past Due	1,258
Total Past Due	1,522	209
Current Loans	23,795	34,437
Total loans	25,317	34,646
Covered Loans \| Commercial Loans \| Agricultural
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	43	164
Total loans	43	164
Covered Loans \| Commercial Loans \| Farmland Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	3
90+ Days Past Due		301
Total Past Due	3	301
Current Loans	713	572
Total loans	716	873
Covered Loans \| Consumer Real Estate \| Home Equity Lines
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	858	488
60 - 89 Days Past Due	318	86
90+ Days Past Due	168	163
Total Past Due	1,344	737
Current Loans	59,047	68,469
Total loans	60,391	69,206
Covered Loans \| Consumer Real Estate \| Single Family Owner Occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	134	197
60 - 89 Days Past Due	34	120
90+ Days Past Due	415	1,466
Total Past Due	583	1,783
Current Loans	11,385	15,136
Total loans	11,968	16,919
Covered Loans \| Consumer Real Estate \| Owner occupied construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
90+ Days Past Due		190
Total Past Due		190
Current Loans	453	994
Total loans	453	1,184
Covered Loans \| Consumer and Other \| Consumer Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	88	118
Total loans	$ 88	$ 118

Aging of Past Due Loans by Loan Class (Detail) (USD $)
In Thousands, unless otherwise specified

Dec. 31, 2014

Dec. 31, 2013

Financing Receivable, Recorded Investment, Past Due [Line Items]

30 - 59 Days Past Due

$ 10,400

$ 12,307

60 - 89 Days Past Due