Securities - Aggregate Amortized Costs and Fair Values of Available-for-Sale Securities (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 76,409	$ 77,773
Gross Unrealized Gains	44	224
Gross Unrealized (Losses)	(2,131)	(844)
Fair Value	74,322	77,153
US Government Agencies Agencies and Mortgage Backed Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	48,032	49,964
Gross Unrealized Gains	2	6
Gross Unrealized (Losses)	(1,707)	(687)
Fair Value	46,327	49,283
State and Municipal Obligations
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	21,281	21,113
Gross Unrealized Gains	32	195
Gross Unrealized (Losses)	(422)	(155)
Fair Value	20,891	21,153
Corporate Bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	7,096	6,696
Gross Unrealized Gains	10	23
Gross Unrealized (Losses)	(2)	(2)
Fair Value	$ 7,104	$ 6,717

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
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-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109979856&loc=d3e26610-111562

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