Securities - Amortized cost, gross unrealized gains and losses, and fair value of debt securities held-to-maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Held-to-maturity securities:
Amortized Cost	$ 290,404	$ 283,533
Gross Unrealized Gains	11,258	5,215
Gross Unrealized Losses	67	844
Fair Value	301,595	287,904
State and political subdivisions
Held-to-maturity securities:
Amortized Cost	61,083	45,479
Gross Unrealized Gains	3,377	1,574
Gross Unrealized Losses	0	9
Fair Value	64,460	47,044
Residential mortgage-backed securities, Agency
Held-to-maturity securities:
Amortized Cost	145,793	153,967
Gross Unrealized Gains	4,711	2,014
Gross Unrealized Losses	14	694
Fair Value	150,490	155,287
Commercial mortgage-backed, Agency
Held-to-maturity securities:
Amortized Cost	83,528	84,087
Gross Unrealized Gains	3,170	1,627
Gross Unrealized Losses	53	141
Fair Value	$ 86,645	$ 85,573

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

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-Publisher FASB
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Amount of accumulated unrecognized gain on investment in debt security measured at amortized cost (held-to-maturity).

+ References

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

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