Loans and Leases - Credit Quality Indicators (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	$ 2,390,832	$ 1,883,563
Total Loans and Leases Held for Investment, Acquired	895,054	295,450
Grade: 1. Cash secured/ 2. Fully secured [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	14,148	6,385
Total Loans and Leases Held for Investment, Acquired	583	1,411
Grade: 3. Strong [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	17,025	28,205
Total Loans and Leases Held for Investment, Acquired	0	0
Grade: 4. Satisfactory [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	74,757	73,179
Total Loans and Leases Held for Investment, Acquired	5,417	5,350
Grade: 5. Acceptable [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	1,386,253	1,010,195
Total Loans and Leases Held for Investment, Acquired	533,598	238,207
Grade: 6. Pre-watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	272,383	200,638
Total Loans and Leases Held for Investment, Acquired	221,113	20,791
Grade: 7. Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	32,772	28,707
Total Loans and Leases Held for Investment, Acquired	14,023	9,637
Grade: 8. Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	70,286	78,197
Total Loans and Leases Held for Investment, Acquired	24,769	4,829
Grade: 9. Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	0	0
Total Loans and Leases Held for Investment, Acquired	0	0
Grade: 10. Loss [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	0	0
Total Loans and Leases Held for Investment, Acquired	0	0
Internally Assigned Grades [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	1,867,624	1,425,506
Total Loans and Leases Held for Investment, Acquired	799,503	280,225
Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	521,472	456,156
Total Loans and Leases Held for Investment, Acquired	94,679	15,225
Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	1,736	1,901
Total Loans and Leases Held for Investment, Acquired	872	0
Performing and Nonperforming [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	523,208	458,057
Total Loans and Leases Held for Investment, Acquired	95,551	15,225
Commercial, Financial and Agricultural [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	663,221	479,980
Total Loans and Leases Held for Investment, Acquired	160,045	24,535
Commercial, Financial and Agricultural [Member] | Grade: 1. Cash secured/ 2. Fully secured [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	272	968
Total Loans and Leases Held for Investment, Acquired	583	1,411
Commercial, Financial and Agricultural [Member] | Grade: 3. Strong [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	14,980	17,328
Total Loans and Leases Held for Investment, Acquired	0	0
Commercial, Financial and Agricultural [Member] | Grade: 4. Satisfactory [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	35,529	36,697
Total Loans and Leases Held for Investment, Acquired	4,399	1,181
Commercial, Financial and Agricultural [Member] | Grade: 5. Acceptable [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	465,675	328,140
Total Loans and Leases Held for Investment, Acquired	113,512	18,446
Commercial, Financial and Agricultural [Member] | Grade: 6. Pre-watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	113,499	61,098
Total Loans and Leases Held for Investment, Acquired	31,697	2,273
Commercial, Financial and Agricultural [Member] | Grade: 7. Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	8,820	6,074
Total Loans and Leases Held for Investment, Acquired	73	417
Commercial, Financial and Agricultural [Member] | Grade: 8. Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	24,446	29,675
Total Loans and Leases Held for Investment, Acquired	9,781	807
Commercial, Financial and Agricultural [Member] | Grade: 9. Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	0	0
Total Loans and Leases Held for Investment, Acquired	0	0
Commercial, Financial and Agricultural [Member] | Grade: 10. Loss [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	0	0
Total Loans and Leases Held for Investment, Acquired	0	0
Commercial, Financial and Agricultural [Member] | Internally Assigned Grades [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	663,221	479,980
Total Loans and Leases Held for Investment, Acquired	160,045	24,535
Real Estate-Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	909,581	759,342
Total Loans and Leases Held for Investment, Acquired	465,368	126,550
Real Estate-Commercial [Member] | Grade: 1. Cash secured/ 2. Fully secured [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	0	0
Total Loans and Leases Held for Investment, Acquired	0	0
Real Estate-Commercial [Member] | Grade: 3. Strong [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	2,045	10,877
Total Loans and Leases Held for Investment, Acquired	0	0
Real Estate-Commercial [Member] | Grade: 4. Satisfactory [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	38,861	36,023
Total Loans and Leases Held for Investment, Acquired	1,018	3,561
Real Estate-Commercial [Member] | Grade: 5. Acceptable [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	676,212	530,766
Total Loans and Leases Held for Investment, Acquired	282,199	102,122
Real Estate-Commercial [Member] | Grade: 6. Pre-watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	128,646	119,117
Total Loans and Leases Held for Investment, Acquired	163,623	10,365
Real Estate-Commercial [Member] | Grade: 7. Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	22,439	20,286
Total Loans and Leases Held for Investment, Acquired	7,705	8,853
Real Estate-Commercial [Member] | Grade: 8. Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	41,378	42,273
Total Loans and Leases Held for Investment, Acquired	10,823	1,649
Real Estate-Commercial [Member] | Grade: 9. Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	0	0
Total Loans and Leases Held for Investment, Acquired	0	0
Real Estate-Commercial [Member] | Grade: 10. Loss [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	0	0
Total Loans and Leases Held for Investment, Acquired	0	0
Real Estate-Commercial [Member] | Internally Assigned Grades [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	909,581	759,342
Total Loans and Leases Held for Investment, Acquired	465,368	126,550
Real Estate-Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	142,891	91,904
Total Loans and Leases Held for Investment, Acquired	31,953	4,637
Real Estate-Construction [Member] | Grade: 1. Cash secured/ 2. Fully secured [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	13,714	5,417
Total Loans and Leases Held for Investment, Acquired	0	0
Real Estate-Construction [Member] | Grade: 3. Strong [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	0	0
Total Loans and Leases Held for Investment, Acquired	0	0
Real Estate-Construction [Member] | Grade: 4. Satisfactory [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	0	450
Total Loans and Leases Held for Investment, Acquired	0	0
Real Estate-Construction [Member] | Grade: 5. Acceptable [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	110,650	72,630
Total Loans and Leases Held for Investment, Acquired	20,565	4,637
Real Estate-Construction [Member] | Grade: 6. Pre-watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	18,213	13,262
Total Loans and Leases Held for Investment, Acquired	11,388	0
Real Estate-Construction [Member] | Grade: 7. Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	314	0
Total Loans and Leases Held for Investment, Acquired	0	0
Real Estate-Construction [Member] | Grade: 8. Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	0	145
Total Loans and Leases Held for Investment, Acquired	0	0
Real Estate-Construction [Member] | Grade: 9. Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	0	0
Total Loans and Leases Held for Investment, Acquired	0	0
Real Estate-Construction [Member] | Grade: 10. Loss [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	0	0
Total Loans and Leases Held for Investment, Acquired	0	0
Real Estate-Construction [Member] | Internally Assigned Grades [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	142,891	91,904
Total Loans and Leases Held for Investment, Acquired	31,953	4,637
Real Estate-Residential Secured for Business Purpose [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	151,931	94,280
Total Loans and Leases Held for Investment, Acquired	142,137	124,503
Real Estate-Residential Secured for Business Purpose [Member] | Grade: 1. Cash secured/ 2. Fully secured [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	162	0
Total Loans and Leases Held for Investment, Acquired	0	0
Real Estate-Residential Secured for Business Purpose [Member] | Grade: 3. Strong [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	0	0
Total Loans and Leases Held for Investment, Acquired	0	0
Real Estate-Residential Secured for Business Purpose [Member] | Grade: 4. Satisfactory [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	367	9
Total Loans and Leases Held for Investment, Acquired	0	608
Real Estate-Residential Secured for Business Purpose [Member] | Grade: 5. Acceptable [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	133,716	78,659
Total Loans and Leases Held for Investment, Acquired	117,322	113,002
Real Estate-Residential Secured for Business Purpose [Member] | Grade: 6. Pre-watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	12,025	7,161
Total Loans and Leases Held for Investment, Acquired	14,405	8,153
Real Estate-Residential Secured for Business Purpose [Member] | Grade: 7. Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	1,199	2,347
Total Loans and Leases Held for Investment, Acquired	6,245	367
Real Estate-Residential Secured for Business Purpose [Member] | Grade: 8. Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	4,462	6,104
Total Loans and Leases Held for Investment, Acquired	4,165	2,373
Real Estate-Residential Secured for Business Purpose [Member] | Grade: 9. Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	0	0
Total Loans and Leases Held for Investment, Acquired	0	0
Real Estate-Residential Secured for Business Purpose [Member] | Grade: 10. Loss [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	0	0
Total Loans and Leases Held for Investment, Acquired	0	0
Real Estate-Residential Secured for Business Purpose [Member] | Internally Assigned Grades [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	151,931	94,280
Total Loans and Leases Held for Investment, Acquired	142,137	124,503
Real Estate-Residential Secured for Personal Purpose [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	210,377	177,850
Total Loans and Leases Held for Investment, Acquired	80,431	3,305
Real Estate-Residential Secured for Personal Purpose [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	210,208	177,053
Total Loans and Leases Held for Investment, Acquired	79,559	3,305
Real Estate-Residential Secured for Personal Purpose [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	169	797
Total Loans and Leases Held for Investment, Acquired	872	0
Real Estate-Residential Secured for Personal Purpose [Member] | Performing and Nonperforming [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	210,377	177,850
Total Loans and Leases Held for Investment, Acquired	80,431	3,305
Real Estate-Home Equity Secured for Personal Purpose [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	147,982	125,361
Total Loans and Leases Held for Investment, Acquired	14,857	11,594
Real Estate-Home Equity Secured for Personal Purpose [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	147,286	125,086
Total Loans and Leases Held for Investment, Acquired	14,857	11,594
Real Estate-Home Equity Secured for Personal Purpose [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	696	275
Total Loans and Leases Held for Investment, Acquired	0	0
Real Estate-Home Equity Secured for Personal Purpose [Member] | Performing and Nonperforming [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	147,982	125,361
Total Loans and Leases Held for Investment, Acquired	14,857	11,594
Loans to Individuals [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	30,110	29,406
Total Loans and Leases Held for Investment, Acquired	263	326
Loans to Individuals [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	29,968	29,233
Total Loans and Leases Held for Investment, Acquired	263	326
Loans to Individuals [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	142	173
Total Loans and Leases Held for Investment, Acquired	0	0
Loans to Individuals [Member] | Performing and Nonperforming [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	30,110	29,406
Total Loans and Leases Held for Investment, Acquired	263	326
Lease Financings [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	134,739	125,440
Total Loans and Leases Held for Investment, Acquired	0	0
Lease Financings [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	134,010	124,784
Total Loans and Leases Held for Investment, Acquired	0	0
Lease Financings [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	729	656
Total Loans and Leases Held for Investment, Acquired	0	0
Lease Financings [Member] | Performing and Nonperforming [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans and Leases Held for Investment, Originated	134,739	125,440
Total Loans and Leases Held for Investment, Acquired	$ 0	$ 0