Summary of Investments - Net Realized Investment Gains and Losses and Proceeds (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Net realized investment gains (losses):
Available-for-sale	$ 294	$ 52	$ (207)	$ 52
Allowance for credit losses	170	2	5	(8)
Trading Securities	0	382	0	(780)
Mortgage loans allowance for credit losses	5	0	5	(4)
Real estate	(256)	0	(256)	(28)
Total net realized investment gains (losses)	(2,269)	15,212	28,243	(62,416)
Proceeds from sale of available-for-sale investments			170,637	16,907
Fixed maturities
Net realized investment gains (losses):
Proceeds from sale of available-for-sale investments	53,973	0	170,637	16,907
Gross realized gains	690	0	843	198
Gross realized losses	396	0	1,051	495
Change in the fair value
Net realized investment gains (losses):
Equity securities	(1,314)	21,962	20,513	(38,876)
Sales
Net realized investment gains (losses):
Equity securities	$ (1,168)	$ (7,186)	$ 8,183	$ (22,772)

Amount of expense (reversal of expense) for expected credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), from change in present value of expected cash flows.

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