Investments - Cost and Fair Value, Net of Credit Loss Allowance, of Available-For-Sale Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Available-for-sale securities
Amortized cost	$ 968,861
Estimated fair value	915,666
Corporate debt securities
Available-for-sale securities
Amortized cost	596,754	$ 588,536
Gross unrealized gains	1,149	657
Gross unrealized losses	29,372	35,811
Estimated fair value	568,531	553,382
Collateralized debt obligations
Available-for-sale securities
Amortized cost	109,662	107,730
Gross unrealized gains	19	11
Gross unrealized losses	4,654	5,204
Estimated fair value	105,027	102,537
Commercial mortgage-backed securities
Available-for-sale securities
Amortized cost	72,549	73,855
Gross unrealized gains	181	157
Gross unrealized losses	6,298	7,958
Estimated fair value	66,432	66,054
Residential mortgage-backed securities
Available-for-sale securities
Amortized cost	170,409	166,412
Gross unrealized gains	273	72
Gross unrealized losses	13,380	16,069
Estimated fair value	157,302	150,415
Other debt securities
Available-for-sale securities
Amortized cost	19,487	24,602
Gross unrealized gains	69	0
Gross unrealized losses	1,182	2,329
Estimated fair value	18,374	22,273
Available-for-sale securities
Available-for-sale securities
Amortized cost	968,861	961,135
Gross unrealized gains	1,691	897
Gross unrealized losses	54,886	67,371
Estimated fair value	$ 915,666	$ 894,661

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on 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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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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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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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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