Fair Value - Fair Value Measurements on a Recurring Basis by Asset Class and Level of Input (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	$ 1,043,615
Available-for-sale securities
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	1,043,615	$ 961,241
Corporate debt securities
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	643,943	588,688
Collateralized debt obligations
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	114,127	112,468
Commercial mortgage-backed securities
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	124,982	102,720
Residential mortgage-backed securities
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	133,812	140,055
Other debt securities
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	26,751	17,310
Fair Value, Measurements, Recurring Basis
Fair value measurements on a recurring basis by asset class and level of input
Total	1,129,506	1,045,494
Fair Value, Measurements, Recurring Basis | Available-for-sale securities
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	1,043,615	961,241
Fair Value, Measurements, Recurring Basis | Corporate debt securities
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	643,943	588,688
Fair Value, Measurements, Recurring Basis | Collateralized debt obligations
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	114,127	112,468
Fair Value, Measurements, Recurring Basis | Commercial mortgage-backed securities
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	124,982	102,720
Fair Value, Measurements, Recurring Basis | Residential mortgage-backed securities
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	133,812	140,055
Fair Value, Measurements, Recurring Basis | Other debt securities
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	26,751	17,310
Fair Value, Measurements, Recurring Basis | Equity securities
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities	85,891	84,253
Fair Value, Measurements, Recurring Basis | Equity securities | Financial services sector
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities	69,930	69,900
Fair Value, Measurements, Recurring Basis | Equity securities | Utilities sector
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities	5,629	5,810
Fair Value, Measurements, Recurring Basis | Equity securities | Energy sector
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities	4,117	3,901
Fair Value, Measurements, Recurring Basis | Equity securities | Consumer sector
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities	3,341	3,915
Fair Value, Measurements, Recurring Basis | Equity securities | Technology sector
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities	1,974	500
Fair Value, Measurements, Recurring Basis | Equity securities | Industrial sector
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities		180
Fair Value, Measurements, Recurring Basis | Equity securities | Communications sector
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities	900	47
Fair Value, Measurements, Recurring Basis | Level 1
Fair value measurements on a recurring basis by asset class and level of input
Total	1,106	863
Fair Value, Measurements, Recurring Basis | Level 1 | Available-for-sale securities
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	0	0
Fair Value, Measurements, Recurring Basis | Level 1 | Corporate debt securities
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	0	0
Fair Value, Measurements, Recurring Basis | Level 1 | Collateralized debt obligations
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	0	0
Fair Value, Measurements, Recurring Basis | Level 1 | Commercial mortgage-backed securities
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	0	0
Fair Value, Measurements, Recurring Basis | Level 1 | Residential mortgage-backed securities
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	0	0
Fair Value, Measurements, Recurring Basis | Level 1 | Other debt securities
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	0	0
Fair Value, Measurements, Recurring Basis | Level 1 | Equity securities
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities	1,106	863
Fair Value, Measurements, Recurring Basis | Level 1 | Equity securities | Financial services sector
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities	1,052	816
Fair Value, Measurements, Recurring Basis | Level 1 | Equity securities | Utilities sector
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities	0	0
Fair Value, Measurements, Recurring Basis | Level 1 | Equity securities | Energy sector
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities	0	0
Fair Value, Measurements, Recurring Basis | Level 1 | Equity securities | Consumer sector
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities	54	0
Fair Value, Measurements, Recurring Basis | Level 1 | Equity securities | Technology sector
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities	0	0
Fair Value, Measurements, Recurring Basis | Level 1 | Equity securities | Industrial sector
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities		0
Fair Value, Measurements, Recurring Basis | Level 1 | Equity securities | Communications sector
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities	0	47
Fair Value, Measurements, Recurring Basis | Level 2
Fair value measurements on a recurring basis by asset class and level of input
Total	1,091,069	1,020,263
Fair Value, Measurements, Recurring Basis | Level 2 | Available-for-sale securities
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	1,013,258	944,207
Fair Value, Measurements, Recurring Basis | Level 2 | Corporate debt securities
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	637,675	584,182
Fair Value, Measurements, Recurring Basis | Level 2 | Collateralized debt obligations
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	114,127	112,468
Fair Value, Measurements, Recurring Basis | Level 2 | Commercial mortgage-backed securities
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	100,893	91,726
Fair Value, Measurements, Recurring Basis | Level 2 | Residential mortgage-backed securities
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	133,812	138,521
Fair Value, Measurements, Recurring Basis | Level 2 | Other debt securities
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	26,751	17,310
Fair Value, Measurements, Recurring Basis | Level 2 | Equity securities
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities	77,811	76,056
Fair Value, Measurements, Recurring Basis | Level 2 | Equity securities | Financial services sector
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities	65,378	63,750
Fair Value, Measurements, Recurring Basis | Level 2 | Equity securities | Utilities sector
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities	5,629	5,810
Fair Value, Measurements, Recurring Basis | Level 2 | Equity securities | Energy sector
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities	4,117	3,901
Fair Value, Measurements, Recurring Basis | Level 2 | Equity securities | Consumer sector
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities	1,787	2,415
Fair Value, Measurements, Recurring Basis | Level 2 | Equity securities | Technology sector
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities	0	0
Fair Value, Measurements, Recurring Basis | Level 2 | Equity securities | Industrial sector
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities		180
Fair Value, Measurements, Recurring Basis | Level 2 | Equity securities | Communications sector
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities	900	0
Fair Value, Measurements, Recurring Basis | Level 3
Fair value measurements on a recurring basis by asset class and level of input
Total	37,331	24,368
Fair Value, Measurements, Recurring Basis | Level 3 | Available-for-sale securities
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	30,357	17,034
Fair Value, Measurements, Recurring Basis | Level 3 | Corporate debt securities
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	6,268	4,506
Fair Value, Measurements, Recurring Basis | Level 3 | Collateralized debt obligations
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	0	0
Fair Value, Measurements, Recurring Basis | Level 3 | Commercial mortgage-backed securities
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	24,089	10,994
Fair Value, Measurements, Recurring Basis | Level 3 | Residential mortgage-backed securities
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	0	1,534
Fair Value, Measurements, Recurring Basis | Level 3 | Other debt securities
Fair value measurements on a recurring basis by asset class and level of input
Total available-for-sale securities	0	0
Fair Value, Measurements, Recurring Basis | Level 3 | Equity securities
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities	6,974	7,334
Fair Value, Measurements, Recurring Basis | Level 3 | Equity securities | Financial services sector
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities	3,500	5,334
Fair Value, Measurements, Recurring Basis | Level 3 | Equity securities | Utilities sector
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities	0	0
Fair Value, Measurements, Recurring Basis | Level 3 | Equity securities | Energy sector
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities	0	0
Fair Value, Measurements, Recurring Basis | Level 3 | Equity securities | Consumer sector
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities	1,500	1,500
Fair Value, Measurements, Recurring Basis | Level 3 | Equity securities | Technology sector
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities	1,974	500
Fair Value, Measurements, Recurring Basis | Level 3 | Equity securities | Industrial sector
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities		0
Fair Value, Measurements, Recurring Basis | Level 3 | Equity securities | Communications sector
Fair value measurements on a recurring basis by asset class and level of input
Total equity securities	$ 0	$ 0