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Securities - Summary of Amortized Costs and Fair Values of Securities (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Securities available for sale:
Amortized Cost	$ 89,888	$ 96,106
Gross Unrealized Gains	550	333
Gross Unrealized (Losses)	(697)	(1,637)
Fair Value	89,741	94,802	[1]
Securities held to maturity:
Amortized Cost	50,824	53,398
Gross Unrealized Gains	387	19
Gross Unrealized (Losses)	(210)	(708)
Fair Value	51,001	52,709	[1]
Total securities, Amortized cost	140,712	149,504
Total securities, Gross unrealized gains	937	352
Total securities, Gross unrealized (losses)	(907)	(2,345)
Total securities, Fair value	140,742	147,511
U.S. agency and mortgage-backed securities
Securities available for sale:
Amortized Cost	74,574	81,451
Gross Unrealized Gains	298	177
Gross Unrealized (Losses)	(644)	(1,457)
Fair Value	74,228	80,171
Securities held to maturity:
Amortized Cost	34,730	37,269
Gross Unrealized Gains	93	1
Gross Unrealized (Losses)	(200)	(483)
Fair Value	34,623	36,787
Obligations of states and political subdivisions
Securities available for sale:
Amortized Cost	15,313	14,654
Gross Unrealized Gains	241	146
Gross Unrealized (Losses)	(53)	(180)
Fair Value	15,501	14,620
Securities held to maturity:
Amortized Cost	14,594	14,629
Gross Unrealized Gains	294	18
Gross Unrealized (Losses)	0	(211)
Fair Value	14,888	14,436
Corporate equity securities
Securities available for sale:
Amortized Cost	1	1
Gross Unrealized Gains	11	10
Gross Unrealized (Losses)	0	0
Fair Value	12	11
Corporate debt securities
Securities held to maturity:
Amortized Cost	1,500	1,500
Gross Unrealized Gains	0	0
Gross Unrealized (Losses)	(10)	(14)
Fair Value	$ 1,490	$ 1,486
[1] Derived from audited consolidated financial statements.

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