Securities - Components of Available for Sale Portfolio (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Schedule of Available-for-sale Securities [Line Items]
Total amortized cost	$ 238,414	$ 246,426
Available-for-sale securities, Gross unrealized gains	826	277
Available-for-sale securities, Gross unrealized losses	(1,819)	(5,060)
Available-for-sale securities, Total fair value	237,421	241,643
U.S. Treasury and Agency Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total amortized cost	97,609	97,785
Available-for-sale securities, Gross unrealized gains	43
Available-for-sale securities, Gross unrealized losses	(559)	(2,204)
Available-for-sale securities, Total fair value	97,093	95,581
States and Municipalities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total amortized cost	31,060	48,167
Available-for-sale securities, Gross unrealized gains	263	107
Available-for-sale securities, Gross unrealized losses	(13)	(528)
Available-for-sale securities, Total fair value	31,310	47,746
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total amortized cost	2,000	2,000
Available-for-sale securities, Gross unrealized gains	26	4
Available-for-sale securities, Total fair value	2,026	2,004
Collateralized Mortgage Obligations (CMO) [Member]
Schedule of Available-for-sale Securities [Line Items]
Total amortized cost	33,101	21,979
Available-for-sale securities, Gross unrealized gains	468	143
Available-for-sale securities, Gross unrealized losses		(14)
Available-for-sale securities, Total fair value	33,569	22,108
Mortgage-Backed Securities (MBS) [Member]
Schedule of Available-for-sale Securities [Line Items]
Total amortized cost	74,644	76,495
Available-for-sale securities, Gross unrealized gains	26	23
Available-for-sale securities, Gross unrealized losses	(1,247)	(2,314)
Available-for-sale securities, Total fair value	$ 73,423	$ 74,204

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).

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-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).

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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).

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-Publisher FASB
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