Investments (Unrealized Losses) (Details)	3 Months Ended
	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Writeoff	$ 0	$ 0
Debt security maturities rated investment grade, percent	99.00%		99.40%
US Treasury Securities [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 1,178,000		$ 1,203,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 67,000		$ 40,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions	5		5
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 66,000		$ 65,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 7,000		$ 8,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions	2		2
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 1,244,000		$ 1,268,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 74,000		$ 48,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions	7		7
US Government Agencies Debt Securities [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 220,000		$ 221,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 1,000		$ 1,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions	1		1
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 0		$ 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 0		$ 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions	0		0
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 220,000		$ 221,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 1,000		$ 1,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions	1		1
US States and Political Subdivisions Debt Securities [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 22,031,000		$ 19,540,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 357,000		$ 357,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions	41		35
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 165,011,000		$ 164,264,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 29,670,000		$ 28,775,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions	196		192
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 187,042,000		$ 183,804,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 30,027,000		$ 29,132,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions	237		227
Corporate Debt Securities Financial Sector Member [Domain]
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 9,895,000		$ 12,584,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 380,000		$ 383,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions	26		19
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 178,234,000		$ 176,521,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 32,079,000		$ 30,872,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions	218		217
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 188,129,000		$ 189,105,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 32,459,000		$ 31,255,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions	244		236
Corporate Debt Security Consumer Sector
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 13,303,000		$ 10,175,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 643,000		$ 265,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions	29		16
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 174,217,000		$ 176,725,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 38,972,000		$ 36,829,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions	224		223
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 187,520,000		$ 186,900,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 39,615,000		$ 37,094,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions	253		239
Corporate Debt Security Utilities Sector
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 9,200,000		$ 3,596,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 374,000		$ 66,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions	45		20
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 83,296,000		$ 85,169,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 21,202,000		$ 20,187,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions	136		137
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 92,496,000		$ 88,765,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 21,576,000		$ 20,253,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions	181		157
Corporate Debt Security Energy Sector
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 4,380,000		$ 3,291,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 110,000		$ 57,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions	3		1
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 58,299,000		$ 59,392,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 8,466,000		$ 7,992,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions	74		76
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 62,679,000		$ 62,683,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 8,576,000		$ 8,049,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions	77		77
Corporate Debt Security Communications Sector
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 6,429,000		$ 5,784,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 190,000		$ 153,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions	6		5
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 54,172,000		$ 56,108,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 9,653,000		$ 8,739,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions	68		69
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 60,601,000		$ 61,892,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 9,843,000		$ 8,892,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions	74		74
Corporate Debt Security All Other Sector
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 4,147,000		$ 2,080,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 121,000		$ 32,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions	9		5
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 83,944,000		$ 85,757,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 14,168,000		$ 12,407,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions	100		100
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 88,091,000		$ 87,837,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 14,289,000		$ 12,439,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions	109		105
Commercial Mortgage Backed Securities [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 100,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 5,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions	1
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 100,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 5,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions	1
Residential Mortgage Backed Securities [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 133,000		$ 849,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 2,000		$ 38,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions	7		5
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 94,337,000		$ 95,806,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 12,134,000		$ 10,022,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions	86		86
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 94,470,000		$ 96,655,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 12,136,000		$ 10,060,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions	93		91
Asset-backed Securities [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 6,793,000		$ 4,757,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 60,000		$ 111,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions	10		8
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 22,959,000		$ 32,764,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 988,000		$ 1,405,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions	29		40
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 29,752,000		$ 37,521,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 1,048,000		$ 1,516,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions	39		48
Debt Securities [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 77,709,000		$ 64,080,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 2,305,000		$ 1,503,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions	182		120
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 914,635,000		$ 932,571,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 167,344,000		$ 157,236,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions	1,134		1,142
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 992,344,000		$ 996,651,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 169,649,000		$ 158,739,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions	1,316		1,262