Investments - Estimated Fair Value of Contractual Maturities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost [Abstract]
Maturing within one year, Amortized Cost	$ 7,037	$ 7,155
Maturing after one year through five years, Amortized Cost	15,424	17,008
Maturing after five years through ten years, Amortized Cost	35,850	33,805
Maturing after ten years, Amortized Cost	148,842	136,057
Investment securities not due at a single maturity date, Amortized Cost	194,774
Amortized Cost	600,832	592,378
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Fair Value [Abstract]
Maturing within one year, Fair Value	7,158	7,244
Maturing after one year through five years, Fair Value	15,631	17,171
Maturing after five years through ten years, Fair Value	36,927	34,881
Maturing after ten years, Fair Value	155,192	141,114
Fair Value, Total	620,154	600,799
States and Political Subdivisions [Member]
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost [Abstract]
Amortized Cost	195,565	181,900
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Fair Value [Abstract]
Fair Value, Total	203,166	188,265
Mortgage-backed Securities [Member]
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost [Abstract]
Investment securities not due at a single maturity date, Amortized Cost		189,554
Amortized Cost	393,680	398,353
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Fair Value [Abstract]
Investment securities not due at a single maturity date, Fair Value	199,613	190,488
Fair Value, Total	405,246	400,389
Collateralized Mortgage Obligations [Member]
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost [Abstract]
Investment securities not due at a single maturity date, Amortized Cost	198,905	208,799
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Fair Value [Abstract]
Investment securities not due at a single maturity date, Fair Value	$ 205,633	$ 209,901

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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