Risk Category of Loans by Class of Loans (Excluding Mortgage Loans Held for Sale) (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable, gross	$ 571,466	$ 408,313
Unearned discount	352	201
Total	571,114	408,112
Pass
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable, gross	550,602	388,439
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable, gross	7,649	5,814
Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable, gross	13,215	14,000
Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable, gross	0	60
Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable, gross	328,875	260,186
Unearned discount	228	91
Total	328,647	260,095
Commercial Real Estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable, gross	310,903	241,927
Commercial Real Estate | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable, gross	6,338	5,653
Commercial Real Estate | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable, gross	11,634	12,606
Commercial Real Estate | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable, gross	0	0
Mortgage Real Estate
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable, gross	144,516	77,409
Unearned discount	94	94
Total	144,422	77,315
Mortgage Real Estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable, gross	143,200	76,206
Mortgage Real Estate | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable, gross	33	144
Mortgage Real Estate | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable, gross	1,283	1,059
Mortgage Real Estate | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable, gross	0	0
Installment and Other
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable, gross	19,739	16,458
Unearned discount	0	2
Total	19,739	16,456
Installment and Other | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable, gross	19,699	16,426
Installment and Other | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable, gross	0	17
Installment and Other | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable, gross	40	15
Installment and Other | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable, gross	0	0
Commercial,Financial and Agriculture
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable, gross	78,336	54,260
Unearned discount	30	14
Total	78,306	54,246
Commercial,Financial and Agriculture | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable, gross	76,800	53,880
Commercial,Financial and Agriculture | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable, gross	1,278	0
Commercial,Financial and Agriculture | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable, gross	258	320
Commercial,Financial and Agriculture | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable, gross	$ 0	$ 60