Investments, Gross Unrealized Losses and Fair Value and Net Unrealized Gains (Losses) (Details) $ in Thousands	Sep. 30, 2023 USD ($) Security	Dec. 31, 2022 USD ($)
Available-for-sale, Debt Securities, Fair Value and Gross Unrealized Losses [Abstract]
Number of securities owned with fair value less than cost | Security	338
Less than twelve months, Fair value	$ 15,396	$ 181,562
Less than twelve months, Gross unrealized losses	(712)	(11,648)
Twelve months or greater, Fair value	393,093	246,164
Twelve months or greater, Gross unrealized losses	(51,612)	(35,889)
Total, Fair value	408,489	427,726
Total, Gross Unrealized Losses	(52,324)	(47,537)
U.S. Agency Securities [Member]
Available-for-sale, Debt Securities, Fair Value and Gross Unrealized Losses [Abstract]
Less than twelve months, Fair value	0	39,729
Less than twelve months, Gross unrealized losses	0	(1,892)
Twelve months or greater, Fair value	61,646	30,948
Twelve months or greater, Gross unrealized losses	(7,920)	(5,987)
Total, Fair value	61,646	70,677
Total, Gross Unrealized Losses	(7,920)	(7,879)
U.S. Treasury Securities [Member]
Available-for-sale, Debt Securities, Fair Value and Gross Unrealized Losses [Abstract]
Less than twelve months, Fair value	0	32,673
Less than twelve months, Gross unrealized losses	0	(1,337)
Twelve months or greater, Fair value	147,431	115,897
Twelve months or greater, Gross unrealized losses	(12,995)	(12,329)
Total, Fair value	147,431	148,570
Total, Gross Unrealized Losses	(12,995)	(13,666)
Obligations of State and Political Subdivisions [Member]
Available-for-sale, Debt Securities, Fair Value and Gross Unrealized Losses [Abstract]
Less than twelve months, Fair value	4,731	66,725
Less than twelve months, Gross unrealized losses	(130)	(4,887)
Twelve months or greater, Fair value	89,094	35,782
Twelve months or greater, Gross unrealized losses	(12,422)	(5,410)
Total, Fair value	93,825	102,507
Total, Gross Unrealized Losses	(12,552)	(10,297)
Corporate Obligations [Member]
Available-for-sale, Debt Securities, Fair Value and Gross Unrealized Losses [Abstract]
Less than twelve months, Fair value	1,458	2,165
Less than twelve months, Gross unrealized losses	(289)	(165)
Twelve months or greater, Fair value	8,102	6,218
Twelve months or greater, Gross unrealized losses	(1,201)	(787)
Total, Fair value	9,560	8,383
Total, Gross Unrealized Losses	(1,490)	(952)
Mortgage-backed Securities in Government Sponsored Entities [Member]
Available-for-sale, Debt Securities, Fair Value and Gross Unrealized Losses [Abstract]
Less than twelve months, Fair value	9,207	40,270
Less than twelve months, Gross unrealized losses	(293)	(3,367)
Twelve months or greater, Fair value	86,820	57,319
Twelve months or greater, Gross unrealized losses	(17,074)	(11,376)
Total, Fair value	96,027	97,589
Total, Gross Unrealized Losses	$ (17,367)	$ (14,743)