Investment Securities - Summary of Unrealized Losses of Held-to-Maturity Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity, less than 12 months, fair value	$ 0	$ 0
Held-to-maturity, less than 12 months, gross unrealized losses	0	0
Held-to-maturity, 12 months or more, fair value	19,597	36,709
Held-to-maturity, 12 months or more, gross unrealized losses	379	786
Held-to-maturity, fair value	19,597	36,709
Held-to-maturity, gross unrealized losses	379	786
State, county, and municipal securities
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity, less than 12 months, fair value	0	0
Held-to-maturity, less than 12 months, gross unrealized losses	0	0
Held-to-maturity, 12 months or more, fair value	819	1,703
Held-to-maturity, 12 months or more, gross unrealized losses	5	10
Held-to-maturity, fair value	819	1,703
Held-to-maturity, gross unrealized losses	5	10
Mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity, less than 12 months, fair value	0	0
Held-to-maturity, less than 12 months, gross unrealized losses	0	0
Held-to-maturity, 12 months or more, fair value	18,778	35,006
Held-to-maturity, 12 months or more, gross unrealized losses	374	776
Held-to-maturity, fair value	18,778	35,006
Held-to-maturity, gross unrealized losses	$ 374	$ 776

Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in continuous loss position for 12 months or longer.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in unrealized loss position.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
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Fair value of investment in debt security measured at amortized cost (held-to-maturity), in unrealized loss position.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Topic 320
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-Section 50
-Paragraph 6
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Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in continuous loss position for less than 12 months.

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