Investments - Estimated Fair Value of Contractual Maturities (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost [Abstract]
Maturing within one year (remainder of year), Amortized Cost	$ 4,362
Maturing within one year, Amortized Cost	0	$ 7,155
Maturing after one year through five years, Amortized Cost	7,834	17,008
Maturing after five years through ten years, Amortized Cost	29,485	33,805
Maturing after ten years, Amortized Cost	169,854	136,057
Amortized Cost	576,363	592,378
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Fair Value [Abstract]
Maturing within one year (remainder of year), Fair Value	4,388
Maturing within one year, Fair Value	0	7,244
Maturing after one year through five years, Fair Value	8,104	17,171
Maturing after five years through ten years, Fair Value	30,823	34,881
Maturing after ten years, Fair Value	180,533	141,114
Fair Value, Total	599,333	600,799
States and Political Subdivisions [Member]
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost [Abstract]
Amortized Cost	209,760	181,900
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Fair Value [Abstract]
Fair Value, Total	221,998	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	181,945	189,554
Amortized Cost	364,828	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	186,880	190,488
Fair Value, Total	375,485	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	182,883	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	$ 188,605	$ 209,901