Loans and Allowance for Loan Losses - Summary of Impaired Loans Disaggregated by Class (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded	$ 11,593	$ 14,958
Recorded Investment, With a related allowance recorded	40,195	20,776
Recorded Investment, Total	51,788	35,734
Unpaid Principal Balance, With no related allowance recorded	14,439	20,589
Unpaid Principal Balance, With a related allowance recorded	47,545	23,356
Unpaid Principal Balance, Total	61,984	43,945
Related Allowance, With no related allowance recorded
Related Allowance, With a related allowance recorded	2,752	768
Related Allowance, Total	2,752	768
Average Recorded Investment, With no related allowance recorded	11,593	23,083
Average Recorded Investment, With a related allowance recorded	40,195	38,833
Average Recorded Investment, Total	51,788	61,916
Interest Income Recognized, With no related allowance recorded	90	534
Interest Income Recognized, With a related allowance recorded	125	703
Interest Income Recognized, Total	215	1,237
Commercial non-real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded	516	2,470
Recorded Investment, With a related allowance recorded	11,111	4,965
Recorded Investment, Total	11,627	7,435
Unpaid Principal Balance, With no related allowance recorded	638	3,717
Unpaid Principal Balance, With a related allowance recorded	13,417	5,303
Unpaid Principal Balance, Total	14,055	9,020
Related Allowance, With no related allowance recorded
Related Allowance, With a related allowance recorded	1,541	477
Related Allowance, Total	1,541	477
Average Recorded Investment, With no related allowance recorded	516	1,100
Average Recorded Investment, With a related allowance recorded	11,111	11,683
Average Recorded Investment, Total	11,627	12,783
Interest Income Recognized, With no related allowance recorded		26
Interest Income Recognized, With a related allowance recorded	81	243
Interest Income Recognized, Total	81	269
Construction and land development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded	3,058	4,829
Recorded Investment, With a related allowance recorded	11,799	6,498
Recorded Investment, Total	14,857	11,327
Unpaid Principal Balance, With no related allowance recorded	3,511	6,273
Unpaid Principal Balance, With a related allowance recorded	14,126	8,343
Unpaid Principal Balance, Total	17,637	14,616
Related Allowance, With no related allowance recorded
Related Allowance, With a related allowance recorded	540	22
Related Allowance, Total	540	22
Average Recorded Investment, With no related allowance recorded	3,058	3,076
Average Recorded Investment, With a related allowance recorded	11,799	2,706
Average Recorded Investment, Total	14,857	5,782
Interest Income Recognized, With no related allowance recorded	22	85
Interest Income Recognized, With a related allowance recorded	39
Interest Income Recognized, Total	61	85
Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded	8,019	7,186
Recorded Investment, With a related allowance recorded	14,736	8,708
Recorded Investment, Total	22,755	15,894
Unpaid Principal Balance, With no related allowance recorded	10,290	10,092
Unpaid Principal Balance, With a related allowance recorded	17,290	9,090
Unpaid Principal Balance, Total	27,580	19,182
Related Allowance, With no related allowance recorded
Related Allowance, With a related allowance recorded	475	268
Related Allowance, Total	475	268
Average Recorded Investment, With no related allowance recorded	8,019	17,225
Average Recorded Investment, With a related allowance recorded	14,736	22,346
Average Recorded Investment, Total	22,755	39,571
Interest Income Recognized, With no related allowance recorded	68	423
Interest Income Recognized, With a related allowance recorded	5	460
Interest Income Recognized, Total	73	883
Residential mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded		473
Recorded Investment, With a related allowance recorded	2,549	605
Recorded Investment, Total	2,549	1,078
Unpaid Principal Balance, With no related allowance recorded		507
Unpaid Principal Balance, With a related allowance recorded	2,712	620
Unpaid Principal Balance, Total	2,712	1,127
Related Allowance, With no related allowance recorded
Related Allowance, With a related allowance recorded	196	1
Related Allowance, Total	196	1
Average Recorded Investment, With no related allowance recorded		669
Average Recorded Investment, With a related allowance recorded	2,549	1,073
Average Recorded Investment, Total	2,549	1,742
Interest Income Recognized, With no related allowance recorded
Interest Income Recognized, With a related allowance recorded
Interest Income Recognized, Total
Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded
Recorded Investment, With a related allowance recorded
Recorded Investment, Total
Unpaid Principal Balance, With no related allowance recorded
Unpaid Principal Balance, With a related allowance recorded
Unpaid Principal Balance, Total
Related Allowance, With no related allowance recorded
Related Allowance, With a related allowance recorded
Related Allowance, Total
Average Recorded Investment, With no related allowance recorded		1,013
Average Recorded Investment, With a related allowance recorded		1,025
Average Recorded Investment, Total		2,038
Interest Income Recognized, With no related allowance recorded
Interest Income Recognized, With a related allowance recorded
Interest Income Recognized, Total
Originated loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded	11,593	9,751
Recorded Investment, With a related allowance recorded	35,140	20,776
Recorded Investment, Total	46,733	30,527
Unpaid Principal Balance, With no related allowance recorded	14,439	13,031
Unpaid Principal Balance, With a related allowance recorded	40,639	23,356
Unpaid Principal Balance, Total	55,078	36,387
Related Allowance, With no related allowance recorded
Related Allowance, With a related allowance recorded	2,350	768
Related Allowance, Total	2,350	768
Average Recorded Investment, With no related allowance recorded	11,593	20,176
Average Recorded Investment, With a related allowance recorded	35,140	32,421
Average Recorded Investment, Total	46,733	52,597
Interest Income Recognized, With no related allowance recorded	90	474
Interest Income Recognized, With a related allowance recorded	20	640
Interest Income Recognized, Total		1,114
Originated loans [Member] | Commercial non-real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded	516	329
Recorded Investment, With a related allowance recorded	9,109	4,965
Recorded Investment, Total	9,625	5,294
Unpaid Principal Balance, With no related allowance recorded	638	442
Unpaid Principal Balance, With a related allowance recorded	9,617	5,303
Unpaid Principal Balance, Total	10,255	5,745
Related Allowance, With no related allowance recorded
Related Allowance, With a related allowance recorded	1,453	477
Related Allowance, Total	1,453	477
Average Recorded Investment, With no related allowance recorded	516	235
Average Recorded Investment, With a related allowance recorded	9,109	8,936
Average Recorded Investment, Total	9,625	9,171
Interest Income Recognized, With no related allowance recorded		18
Interest Income Recognized, With a related allowance recorded	20	180
Interest Income Recognized, Total	54	198
Originated loans [Member] | Construction and land development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded	3,058	4,101
Recorded Investment, With a related allowance recorded	11,064	6,498
Recorded Investment, Total	14,122	10,599
Unpaid Principal Balance, With no related allowance recorded	3,511	5,131
Unpaid Principal Balance, With a related allowance recorded	13,359	8,343
Unpaid Principal Balance, Total	16,870	13,474
Related Allowance, With no related allowance recorded
Related Allowance, With a related allowance recorded	508	22
Related Allowance, Total	508	22
Average Recorded Investment, With no related allowance recorded	3,058	2,780
Average Recorded Investment, With a related allowance recorded	11,064	2,549
Average Recorded Investment, Total	14,122	5,329
Interest Income Recognized, With no related allowance recorded	22	82
Interest Income Recognized, With a related allowance recorded	32
Interest Income Recognized, Total	68	82
Originated loans [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded	8,019	5,321
Recorded Investment, With a related allowance recorded	12,418	8,708
Recorded Investment, Total	20,437	14,029
Unpaid Principal Balance, With no related allowance recorded	10,290	7,458
Unpaid Principal Balance, With a related allowance recorded	14,951	9,090
Unpaid Principal Balance, Total	25,241	16,548
Related Allowance, With no related allowance recorded
Related Allowance, With a related allowance recorded	193	268
Related Allowance, Total	193	268
Average Recorded Investment, With no related allowance recorded	8,019	15,886
Average Recorded Investment, With a related allowance recorded	12,418	19,683
Average Recorded Investment, Total	20,437	35,569
Interest Income Recognized, With no related allowance recorded	68	374
Interest Income Recognized, With a related allowance recorded		460
Interest Income Recognized, Total		834
Originated loans [Member] | Residential mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded
Recorded Investment, With a related allowance recorded	2,549	605
Recorded Investment, Total	2,549	605
Unpaid Principal Balance, With no related allowance recorded
Unpaid Principal Balance, With a related allowance recorded	2,712	620
Unpaid Principal Balance, Total	2,712	620
Related Allowance, With no related allowance recorded
Related Allowance, With a related allowance recorded	196	1
Related Allowance, Total	196	1
Average Recorded Investment, With no related allowance recorded		262
Average Recorded Investment, With a related allowance recorded	2,549	228
Average Recorded Investment, Total	2,549	490
Interest Income Recognized, With no related allowance recorded
Interest Income Recognized, With a related allowance recorded
Interest Income Recognized, Total
Originated loans [Member] | Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded
Recorded Investment, With a related allowance recorded
Recorded Investment, Total
Unpaid Principal Balance, With no related allowance recorded
Unpaid Principal Balance, With a related allowance recorded
Unpaid Principal Balance, Total
Related Allowance, With no related allowance recorded
Related Allowance, With a related allowance recorded
Related Allowance, Total
Average Recorded Investment, With no related allowance recorded		1,013
Average Recorded Investment, With a related allowance recorded		1,025
Average Recorded Investment, Total		2,038
Interest Income Recognized, With no related allowance recorded
Interest Income Recognized, With a related allowance recorded	52
Interest Income Recognized, Total	142
Acquired loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded		5,207
Recorded Investment, With a related allowance recorded	5,055
Recorded Investment, Total	5,055	5,207
Unpaid Principal Balance, With no related allowance recorded		7,558
Unpaid Principal Balance, With a related allowance recorded	6,906
Unpaid Principal Balance, Total	6,906	7,558
Related Allowance, With no related allowance recorded
Related Allowance, With a related allowance recorded	402
Related Allowance, Total	402
Average Recorded Investment, With no related allowance recorded		2,907
Average Recorded Investment, With a related allowance recorded	5,055	6,412
Average Recorded Investment, Total	5,055	9,319
Interest Income Recognized, With no related allowance recorded		60
Interest Income Recognized, With a related allowance recorded	73	63
Interest Income Recognized, Total	73	123
Acquired loans [Member] | Commercial non-real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded		2,141
Recorded Investment, With a related allowance recorded	2,002
Recorded Investment, Total	2,002	2,141
Unpaid Principal Balance, With no related allowance recorded		3,275
Unpaid Principal Balance, With a related allowance recorded	3,800
Unpaid Principal Balance, Total	3,800	3,275
Related Allowance, With no related allowance recorded
Related Allowance, With a related allowance recorded	88
Related Allowance, Total	88
Average Recorded Investment, With no related allowance recorded		865
Average Recorded Investment, With a related allowance recorded	2,002	2,747
Average Recorded Investment, Total	2,002	3,612
Interest Income Recognized, With no related allowance recorded		8
Interest Income Recognized, With a related allowance recorded	61	63
Interest Income Recognized, Total	61	71
Acquired loans [Member] | Construction and land development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded		728
Recorded Investment, With a related allowance recorded	735
Recorded Investment, Total	735	728
Unpaid Principal Balance, With no related allowance recorded		1,142
Unpaid Principal Balance, With a related allowance recorded	767
Unpaid Principal Balance, Total	767	1,142
Related Allowance, With no related allowance recorded
Related Allowance, With a related allowance recorded	32
Related Allowance, Total	32
Average Recorded Investment, With no related allowance recorded		296
Average Recorded Investment, With a related allowance recorded	735	157
Average Recorded Investment, Total	735	453
Interest Income Recognized, With no related allowance recorded		3
Interest Income Recognized, With a related allowance recorded	7
Interest Income Recognized, Total	7	3
Acquired loans [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded		1,865
Recorded Investment, With a related allowance recorded	2,318
Recorded Investment, Total	2,318	1,865
Unpaid Principal Balance, With no related allowance recorded		2,634
Unpaid Principal Balance, With a related allowance recorded	2,339
Unpaid Principal Balance, Total	2,339	2,634
Related Allowance, With no related allowance recorded
Related Allowance, With a related allowance recorded	282
Related Allowance, Total	282
Average Recorded Investment, With no related allowance recorded		1,339
Average Recorded Investment, With a related allowance recorded	2,318	2,663
Average Recorded Investment, Total	2,318	4,002
Interest Income Recognized, With no related allowance recorded		49
Interest Income Recognized, With a related allowance recorded	5
Interest Income Recognized, Total	5	49
Acquired loans [Member] | Residential mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded		473
Recorded Investment, With a related allowance recorded
Recorded Investment, Total		473
Unpaid Principal Balance, With no related allowance recorded		507
Unpaid Principal Balance, With a related allowance recorded
Unpaid Principal Balance, Total		507
Related Allowance, With no related allowance recorded
Related Allowance, With a related allowance recorded
Related Allowance, Total
Average Recorded Investment, With no related allowance recorded		407
Average Recorded Investment, With a related allowance recorded		845
Average Recorded Investment, Total		1,252
Interest Income Recognized, With no related allowance recorded
Interest Income Recognized, With a related allowance recorded
Interest Income Recognized, Total
Acquired loans [Member] | Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded
Recorded Investment, With a related allowance recorded
Recorded Investment, Total
Unpaid Principal Balance, With no related allowance recorded
Unpaid Principal Balance, With a related allowance recorded
Unpaid Principal Balance, Total
Related Allowance, With no related allowance recorded
Related Allowance, With a related allowance recorded
Related Allowance, Total
Average Recorded Investment, With no related allowance recorded
Average Recorded Investment, With a related allowance recorded
Average Recorded Investment, Total
Interest Income Recognized, With no related allowance recorded
Interest Income Recognized, With a related allowance recorded
Interest Income Recognized, Total
Covered loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded
Recorded Investment, With a related allowance recorded
Recorded Investment, Total
Unpaid Principal Balance, With no related allowance recorded
Unpaid Principal Balance, With a related allowance recorded
Unpaid Principal Balance, Total
Related Allowance, With no related allowance recorded
Related Allowance, With a related allowance recorded
Related Allowance, Total
Average Recorded Investment, With no related allowance recorded
Average Recorded Investment, With a related allowance recorded
Average Recorded Investment, Total
Interest Income Recognized, With no related allowance recorded
Interest Income Recognized, With a related allowance recorded
Interest Income Recognized, Total
Covered loans [Member] | Commercial non-real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded
Recorded Investment, With a related allowance recorded
Recorded Investment, Total
Unpaid Principal Balance, With no related allowance recorded
Unpaid Principal Balance, With a related allowance recorded
Unpaid Principal Balance, Total
Related Allowance, With no related allowance recorded
Related Allowance, With a related allowance recorded
Related Allowance, Total
Average Recorded Investment, With no related allowance recorded
Average Recorded Investment, With a related allowance recorded
Average Recorded Investment, Total
Interest Income Recognized, With no related allowance recorded
Interest Income Recognized, With a related allowance recorded
Interest Income Recognized, Total
Covered loans [Member] | Construction and land development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded
Recorded Investment, With a related allowance recorded
Recorded Investment, Total
Unpaid Principal Balance, With no related allowance recorded
Unpaid Principal Balance, With a related allowance recorded
Unpaid Principal Balance, Total
Related Allowance, With no related allowance recorded
Related Allowance, With a related allowance recorded
Related Allowance, Total
Average Recorded Investment, With no related allowance recorded
Average Recorded Investment, With a related allowance recorded
Average Recorded Investment, Total
Interest Income Recognized, With no related allowance recorded
Interest Income Recognized, With a related allowance recorded
Interest Income Recognized, Total
Covered loans [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded
Recorded Investment, With a related allowance recorded
Recorded Investment, Total
Unpaid Principal Balance, With no related allowance recorded
Unpaid Principal Balance, With a related allowance recorded
Unpaid Principal Balance, Total
Related Allowance, With no related allowance recorded
Related Allowance, With a related allowance recorded
Related Allowance, Total
Average Recorded Investment, With no related allowance recorded
Average Recorded Investment, With a related allowance recorded
Average Recorded Investment, Total
Interest Income Recognized, With no related allowance recorded
Interest Income Recognized, With a related allowance recorded
Interest Income Recognized, Total
Covered loans [Member] | Residential mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded
Recorded Investment, With a related allowance recorded
Recorded Investment, Total
Unpaid Principal Balance, With no related allowance recorded
Unpaid Principal Balance, With a related allowance recorded
Unpaid Principal Balance, Total
Related Allowance, With no related allowance recorded
Related Allowance, With a related allowance recorded
Related Allowance, Total
Average Recorded Investment, With no related allowance recorded
Average Recorded Investment, With a related allowance recorded
Average Recorded Investment, Total
Interest Income Recognized, With no related allowance recorded
Interest Income Recognized, With a related allowance recorded
Interest Income Recognized, Total
Covered loans [Member] | Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded
Recorded Investment, With a related allowance recorded
Recorded Investment, Total
Unpaid Principal Balance, With no related allowance recorded
Unpaid Principal Balance, With a related allowance recorded
Unpaid Principal Balance, Total
Related Allowance, With no related allowance recorded
Related Allowance, With a related allowance recorded
Related Allowance, Total
Average Recorded Investment, With no related allowance recorded
Average Recorded Investment, With a related allowance recorded
Average Recorded Investment, Total
Interest Income Recognized, With no related allowance recorded
Interest Income Recognized, With a related allowance recorded
Interest Income Recognized, Total