Fair Value Measurements - Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Assets:
Fair Value	$ 515,064	$ 432,682
Equity securities, at fair value: (cost: $1,724 in 2021, $1,661 in 2020)	38,576	33,261
U.S. Governments
Assets:
Fair Value	48,551	16,870
States, territories, and possessions
Assets:
Fair Value	5,354	4,014
Political subdivisions
Assets:
Fair Value	4,298	6,380
Special revenue excluding mortgage/asset-backed securities
Assets:
Fair Value	32,799	44,498
Industrial and miscellaneous
Assets:
Fair Value	254,095	249,046
Mortgage/asset-backed securities
Assets:
Fair Value	169,967	111,874
Fair Value, Measurements, Recurring
Assets:
Equity securities, at fair value: (cost: $1,724 in 2021, $1,661 in 2020)	38,576	33,261
Cash, cash equivalents, and restricted cash	68,164	50,371
Total assets	621,804	516,314
Fair Value, Measurements, Recurring \| U.S. Governments
Assets:
Fair Value	48,551	16,870
Fair Value, Measurements, Recurring \| States, territories, and possessions
Assets:
Fair Value	5,354	4,014
Fair Value, Measurements, Recurring \| Political subdivisions
Assets:
Fair Value	4,298	6,380
Fair Value, Measurements, Recurring \| Special revenue excluding mortgage/asset-backed securities
Assets:
Fair Value	32,799	44,498
Fair Value, Measurements, Recurring \| Industrial and miscellaneous
Assets:
Fair Value	254,095	249,046
Fair Value, Measurements, Recurring \| Mortgage/asset-backed securities
Assets:
Fair Value	169,967	111,874
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 1
Assets:
Equity securities, at fair value: (cost: $1,724 in 2021, $1,661 in 2020)	38,576	33,261
Cash, cash equivalents, and restricted cash	68,164	50,371
Total assets	106,740	83,632
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 2
Assets:
Total assets	515,064	431,182
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 2 \| U.S. Governments
Assets:
Fair Value	48,551	16,870
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 2 \| States, territories, and possessions
Assets:
Fair Value	5,354	4,014
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 2 \| Political subdivisions
Assets:
Fair Value	4,298	6,380
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 2 \| Special revenue excluding mortgage/asset-backed securities
Assets:
Fair Value	32,799	44,498
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 2 \| Industrial and miscellaneous
Assets:
Fair Value	254,095	249,046
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 2 \| Mortgage/asset-backed securities
Assets:
Fair Value	$ 169,967	110,374
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 3
Assets:
Total assets		1,500
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 3 \| Mortgage/asset-backed securities
Assets:
Fair Value		$ 1,500

Fair value portion of cash, cash equivalents and restricted cash.

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- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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