Securities - Summary of Fair Value of Available for Sale Held to Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Securities available for sale [Abstract]
Amortized Cost	$ 194,330	$ 193,360
Gross unrealized gains	280	1,563
Gross unrealized (losses)	(7,141)	(2,302)
Estimated fair value	187,469	192,621
Securities held to maturity [Abstract]
Amortized Cost	3,740	3,759
Gross unrealized gains	31	89
Gross unrealized (losses)	(5)
Estimated fair value	3,766	3,848
U. S. government agency securities
Securities available for sale [Abstract]
Amortized Cost	11,054	11,433
Gross unrealized gains		12
Gross unrealized (losses)	(589)	(168)
Estimated fair value	10,465	11,277
State and municipal securities
Securities available for sale [Abstract]
Amortized Cost	45,738	51,790
Gross unrealized gains	228	1,430
Gross unrealized (losses)	(1,721)	(222)
Estimated fair value	44,245	52,998
Securities held to maturity [Abstract]
Amortized Cost	3,740	3,759
Gross unrealized gains	31	89
Gross unrealized (losses)	(5)
Estimated fair value	3,766	3,848
Mortgage-backed securities
Securities available for sale [Abstract]
Amortized Cost	109,983	108,236
Gross unrealized gains		40
Gross unrealized (losses)	(4,781)	(1,714)
Estimated fair value	105,202	106,562
Asset-backed securities
Securities available for sale [Abstract]
Amortized Cost	15,687	16,575
Gross unrealized gains	26
Gross unrealized (losses)		(198)
Estimated fair value	15,713	16,377
Other debt securities
Securities available for sale [Abstract]
Amortized Cost	11,868	5,326
Gross unrealized gains	26	81
Gross unrealized (losses)	(50)
Estimated fair value	$ 11,844	$ 5,407

Amortized cost 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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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as 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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Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity).

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Amount, before other-than-temporary impairment (OTTI) accretion, of investment in debt securities measured at amortized cost (held-to-maturity).

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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