Loans Receivable and Allowance for Loan Losses - Troubled Debt Restructurings (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014 Contract	Dec. 31, 2013 Contract
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings at periods end, Number of Contracts	25	12
Troubled debt restructurings at period end, Recorded Investment	$ 4,153	$ 7,535
Accruing [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings at periods end, Number of Contracts	10	6
Troubled debt restructurings at period end, Recorded Investment	1,735	5,988
Accruing [Member] | Commercial Real Estate [Member] | Owner-Occupied [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings at periods end, Number of Contracts	0	1
Troubled debt restructurings at period end, Recorded Investment	0	200
Accruing [Member] | Commercial Real Estate [Member] | Non-Owner Occupied [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings at periods end, Number of Contracts	0	2
Troubled debt restructurings at period end, Recorded Investment	0	4,268
Accruing [Member] | Acquisition and Development [Member] | Commercial and Land Development [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings at periods end, Number of Contracts	2	2
Troubled debt restructurings at period end, Recorded Investment	917	1,071
Accruing [Member] | Residential Mortgage [Member] | First Lien [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings at periods end, Number of Contracts	8	1
Troubled debt restructurings at period end, Recorded Investment	818	449
Nonaccruing [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings at periods end, Number of Contracts	15	6
Troubled debt restructurings at period end, Recorded Investment	2,418	1,547
Nonaccruing [Member] | Commercial Real Estate [Member] | Owner-Occupied [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings at periods end, Number of Contracts	1	1
Troubled debt restructurings at period end, Recorded Investment	49	71
Nonaccruing [Member] | Commercial Real Estate [Member] | Non-Owner Occupied [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings at periods end, Number of Contracts	1	1
Troubled debt restructurings at period end, Recorded Investment	686	694
Nonaccruing [Member] | Commercial Real Estate [Member] | Non-Owner Occupied Residential [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings at periods end, Number of Contracts	0	1
Troubled debt restructurings at period end, Recorded Investment	0	193
Nonaccruing [Member] | Commercial and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings at periods end, Number of Contracts	0	2
Troubled debt restructurings at period end, Recorded Investment	0	310
Nonaccruing [Member] | Residential Mortgage [Member] | First Lien [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings at periods end, Number of Contracts	12	1
Troubled debt restructurings at period end, Recorded Investment	1,669	279
Nonaccruing [Member] | Residential Mortgage [Member] | Consumer Loan [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings at periods end, Number of Contracts	1	0
Troubled debt restructurings at period end, Recorded Investment	$ 14	$ 0