Investments - Contractual Maturities of Available for Sale Fixed Maturity Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Amortized Cost
Due within one year	$ 27,733
Due after one year through five years	134,550
Due after five years through ten years	112,259
Due after ten years	43,944
Mortgage and asset-backed securities	79,469
Amortized Cost	397,955	$ 381,279
Fair Value
Due within one year	27,927
Due after one year through five years	137,757
Due after five years through ten years	116,275
Due after ten years	44,871
Mortgage and asset-backed securities	81,216
Fair Value	$ 408,046	$ 397,987

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in sixth through tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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