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Securities - Estimated fair value of available-for-sale debt securities (Details) - USD ($) $ in Thousands | Jun. 30, 2019 | Dec. 31, 2018
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Contractual Maturities Of Available For Sale Debt Securities [Line Items] |  |
Estimated Fair Value, Due in one year or less | $ 9,263 |
Estimated Fair Value, Due from one to five years | 3,311 |
Estimated Fair Value, Due from five to ten years | 17,524 |
Estimated Fair Value, Due over ten years | 83,470 |
Estimated Fair Value, Total | $ 258,742 | $ 241,768
Tax-Equivalent Yield, Due in one year or less | 2.71% |
Tax-Equivalent Yield, Due from one to five years | 4.91% |
Tax-Equivalent Yield, Due from five to ten years | 3.79% |
Tax-Equivalent Yield, Due over ten years | 4.06% |
Tax-Equivalent Yield, Total | 3.24% |
Collateralized mortgage obligations and residential mortgage-backed securities [Member] |  |
Contractual Maturities Of Available For Sale Debt Securities [Line Items] |  |
Estimated Fair Value, Total | $ 145,174 | $ 135,281
Tax-Equivalent Yield, Total | 2.69% |

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- Definition Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in sixth through tenth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date. + References 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 (d) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27198-111563 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 320 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=75019621&loc=d3e62586-112803 + Details
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- Definition Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27198-111563 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 320 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=75019621&loc=d3e62586-112803 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563 + Details
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