Investment Securities - Estimated Fair Values of Investment Securities (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Total investment securities available for sale, Amortized cost	$ 102,532	$ 85,146
Total investment securities available for sale, Gross unrealized gains	5	155
Total investment securities available for sale, Gross unrealized losses	1,326	3
Total investment securities available for sale, Estimated fair value	101,211	85,298
Total investment securities held-to-maturity, Amortized cost	725	903
Total investment securities held-to-maturity, Gross unrealized gains	35	54
Total investment securities held-to-maturity, Gross unrealized losses	0	0
Total investment securities held-to-maturity, Estimated fair value	760	957
U.S. Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Total investment securities available for sale, Amortized cost	102,423	83,956
Total investment securities available for sale, Gross unrealized gains	2	118
Total investment securities available for sale, Gross unrealized losses	1,325	3
Total investment securities available for sale, Estimated fair value	101,100	84,071
Corporate Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total investment securities available for sale, Amortized cost	44	44
Total investment securities available for sale, Gross unrealized gains	0	0
Total investment securities available for sale, Gross unrealized losses	1	0
Total investment securities available for sale, Estimated fair value	43	44
Total investment securities held-to-maturity, Amortized cost	0
Total investment securities held-to-maturity, Estimated fair value	0
Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total investment securities available for sale, Amortized cost	65	1,146
Total investment securities available for sale, Gross unrealized gains	3	37
Total investment securities available for sale, Gross unrealized losses	0	0
Total investment securities available for sale, Estimated fair value	68	1,183
Total investment securities held-to-maturity, Amortized cost	725	903
Total investment securities held-to-maturity, Gross unrealized gains	35	54
Total investment securities held-to-maturity, Gross unrealized losses	0	0
Total investment securities held-to-maturity, Estimated fair value	$ 760	$ 957