Loans and Allowance for Loan Losses - Schedule of Troubled Debt Restructurings were Modified During Period by Portfolio Segment (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014 Contract	Jun. 30, 2013 Contract
Troubled Debt Restructurings [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts	3	10
Pre-Modification Outstanding Recorded Investment	$ 1,736	$ 4,768
Post-Modification Outstanding Recorded Investment	1,425	4,558
Troubled Debt Restructurings [Member] | Commercial non-real estate [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts		1
Pre-Modification Outstanding Recorded Investment		926
Post-Modification Outstanding Recorded Investment		921
Troubled Debt Restructurings [Member] | Construction and land development [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Pre-Modification Outstanding Recorded Investment
Post-Modification Outstanding Recorded Investment
Troubled Debt Restructurings [Member] | Commercial real estate [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts	1	6
Pre-Modification Outstanding Recorded Investment	963	2,356
Post-Modification Outstanding Recorded Investment	918	2,290
Troubled Debt Restructurings [Member] | Residential mortgages [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts	2	3
Pre-Modification Outstanding Recorded Investment	773	1,486
Post-Modification Outstanding Recorded Investment	507	1,347
Troubled Debt Restructurings [Member] | Consumer [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Pre-Modification Outstanding Recorded Investment
Post-Modification Outstanding Recorded Investment
Troubled Debt Restructurings [Member] | Originated loans [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts	3	8
Pre-Modification Outstanding Recorded Investment	1,736	3,741
Post-Modification Outstanding Recorded Investment	1,425	3,564
Troubled Debt Restructurings [Member] | Originated loans [Member] | Commercial non-real estate [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts		1
Pre-Modification Outstanding Recorded Investment		926
Post-Modification Outstanding Recorded Investment		921
Troubled Debt Restructurings [Member] | Originated loans [Member] | Construction and land development [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Pre-Modification Outstanding Recorded Investment
Post-Modification Outstanding Recorded Investment
Troubled Debt Restructurings [Member] | Originated loans [Member] | Commercial real estate [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts	1	5
Pre-Modification Outstanding Recorded Investment	963	1,844
Post-Modification Outstanding Recorded Investment	918	1,789
Troubled Debt Restructurings [Member] | Originated loans [Member] | Residential mortgages [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts	2	2
Pre-Modification Outstanding Recorded Investment	773	971
Post-Modification Outstanding Recorded Investment	507	854
Troubled Debt Restructurings [Member] | Originated loans [Member] | Consumer [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Pre-Modification Outstanding Recorded Investment
Post-Modification Outstanding Recorded Investment
Troubled Debt Restructurings [Member] | Acquired loans [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts		2
Pre-Modification Outstanding Recorded Investment		1,027
Post-Modification Outstanding Recorded Investment		994
Troubled Debt Restructurings [Member] | Acquired loans [Member] | Commercial non-real estate [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Pre-Modification Outstanding Recorded Investment
Post-Modification Outstanding Recorded Investment
Troubled Debt Restructurings [Member] | Acquired loans [Member] | Construction and land development [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Pre-Modification Outstanding Recorded Investment
Post-Modification Outstanding Recorded Investment
Troubled Debt Restructurings [Member] | Acquired loans [Member] | Commercial real estate [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts		1
Pre-Modification Outstanding Recorded Investment		512
Post-Modification Outstanding Recorded Investment		501
Troubled Debt Restructurings [Member] | Acquired loans [Member] | Residential mortgages [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts		1
Pre-Modification Outstanding Recorded Investment		515
Post-Modification Outstanding Recorded Investment		493
Troubled Debt Restructurings [Member] | Acquired loans [Member] | Consumer [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Pre-Modification Outstanding Recorded Investment
Post-Modification Outstanding Recorded Investment
Troubled Debt Restructurings [Member] | Covered Loans [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Pre-Modification Outstanding Recorded Investment
Post-Modification Outstanding Recorded Investment
Troubled Debt Restructurings [Member] | Covered Loans [Member] | Commercial non-real estate [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Pre-Modification Outstanding Recorded Investment
Post-Modification Outstanding Recorded Investment
Troubled Debt Restructurings [Member] | Covered Loans [Member] | Construction and land development [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Pre-Modification Outstanding Recorded Investment
Post-Modification Outstanding Recorded Investment
Troubled Debt Restructurings [Member] | Covered Loans [Member] | Commercial real estate [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Pre-Modification Outstanding Recorded Investment
Post-Modification Outstanding Recorded Investment
Troubled Debt Restructurings [Member] | Covered Loans [Member] | Residential mortgages [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Pre-Modification Outstanding Recorded Investment
Post-Modification Outstanding Recorded Investment
Troubled Debt Restructurings [Member] | Covered Loans [Member] | Consumer [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Pre-Modification Outstanding Recorded Investment
Post-Modification Outstanding Recorded Investment
Troubled Debt Restructurings That Subsequently Defaulted [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts	3
Recorded Investment	1,934
Troubled Debt Restructurings That Subsequently Defaulted [Member] | Commercial non-real estate [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts	1
Recorded Investment	909
Troubled Debt Restructurings That Subsequently Defaulted [Member] | Construction and land development [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Recorded Investment
Troubled Debt Restructurings That Subsequently Defaulted [Member] | Commercial real estate [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts	2
Recorded Investment	1,025
Troubled Debt Restructurings That Subsequently Defaulted [Member] | Residential mortgages [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Recorded Investment
Troubled Debt Restructurings That Subsequently Defaulted [Member] | Consumer [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Recorded Investment
Troubled Debt Restructurings That Subsequently Defaulted [Member] | Originated loans [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts	3
Recorded Investment	1,934
Troubled Debt Restructurings That Subsequently Defaulted [Member] | Originated loans [Member] | Commercial non-real estate [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts	1
Recorded Investment	909
Troubled Debt Restructurings That Subsequently Defaulted [Member] | Originated loans [Member] | Construction and land development [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Recorded Investment
Troubled Debt Restructurings That Subsequently Defaulted [Member] | Originated loans [Member] | Commercial real estate [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts	2
Recorded Investment	1,025
Troubled Debt Restructurings That Subsequently Defaulted [Member] | Originated loans [Member] | Residential mortgages [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Recorded Investment
Troubled Debt Restructurings That Subsequently Defaulted [Member] | Originated loans [Member] | Consumer [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Recorded Investment
Troubled Debt Restructurings That Subsequently Defaulted [Member] | Acquired loans [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Recorded Investment
Troubled Debt Restructurings That Subsequently Defaulted [Member] | Acquired loans [Member] | Commercial non-real estate [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Recorded Investment
Troubled Debt Restructurings That Subsequently Defaulted [Member] | Acquired loans [Member] | Construction and land development [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Recorded Investment
Troubled Debt Restructurings That Subsequently Defaulted [Member] | Acquired loans [Member] | Commercial real estate [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Recorded Investment
Troubled Debt Restructurings That Subsequently Defaulted [Member] | Acquired loans [Member] | Residential mortgages [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Recorded Investment
Troubled Debt Restructurings That Subsequently Defaulted [Member] | Acquired loans [Member] | Consumer [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Recorded Investment
Troubled Debt Restructurings That Subsequently Defaulted [Member] | Covered Loans [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Recorded Investment
Troubled Debt Restructurings That Subsequently Defaulted [Member] | Covered Loans [Member] | Commercial non-real estate [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Recorded Investment
Troubled Debt Restructurings That Subsequently Defaulted [Member] | Covered Loans [Member] | Construction and land development [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Recorded Investment
Troubled Debt Restructurings That Subsequently Defaulted [Member] | Covered Loans [Member] | Commercial real estate [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Recorded Investment
Troubled Debt Restructurings That Subsequently Defaulted [Member] | Covered Loans [Member] | Residential mortgages [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Recorded Investment
Troubled Debt Restructurings That Subsequently Defaulted [Member] | Covered Loans [Member] | Consumer [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts
Recorded Investment