Securities - Unrealized Loss Positions (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	$ 33,872	$ 34,816
Less than 12 months, Unrealized Loss	(848)	(860)
12 months or more, Fair Value	1,248	1,308
12 months or more, Unrealized Loss	(11)	(12)
Fair Value, Total	35,120	36,124
Total Unrealized Loss	(859)	(872)
Corporate Bonds
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value		995
Less than 12 months, Unrealized Loss		(5)
Fair Value, Total		995
Total Unrealized Loss		(5)
US Government Agencies
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	21,463	20,933
Less than 12 months, Unrealized Loss	(418)	(396)
12 months or more, Fair Value	1,248	1,308
12 months or more, Unrealized Loss	(11)	(12)
Fair Value, Total	22,711	22,241
Total Unrealized Loss	(429)	(408)
State and Municipal Obligations
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	12,409	12,888
Less than 12 months, Unrealized Loss	(430)	(459)
Fair Value, Total	12,409	12,888
Total Unrealized Loss	$ (430)	$ (459)