Investments - Contractual Maturities (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Amortized Cost
Amortized Cost	$ 5,621,453
Less: loaned securities and securities sold under repurchase agreements	137,282	$ 103,996
Total fixed-maturities available for sale	5,535,532	5,367,729
Fair Value
Fair Value	4,985,406
Less: loaned securities and securities sold under repurchase agreements	137,282	103,996
Total fixed-maturities available for sale	4,909,232	5,517,078
Non asset-backed securities
Amortized Cost
Due in one year or less	105,948
Due after one year through five years	1,264,301
Due after five years through 10 years	1,004,494
Due after 10 years	838,992
Fair Value
Due in one year or less	104,459
Due after one year through five years	1,178,849
Due after five years through 10 years	847,994
Due after 10 years	632,035
Asset-backed and mortgage-backed securities
Amortized Cost
Asset-backed and mortgage-backed securities	2,407,718
Fair Value
Asset-backed and mortgage-backed securities	2,222,069
Total fixed-maturities available for sale
Amortized Cost
Total fixed-maturities available for sale	5,535,532	5,367,729
Fair Value
Total fixed-maturities available for sale	4,909,232	5,517,078
Loaned securities, amortized cost
Amortized Cost
Less: loaned securities and securities sold under repurchase agreements	85,921
Fair Value
Less: loaned securities and securities sold under repurchase agreements	85,921
Loaned securities, fair value
Amortized Cost
Less: loaned securities and securities sold under repurchase agreements	76,174
Fair Value
Less: loaned securities and securities sold under repurchase agreements	76,174
Fixed-maturities available for sale \| Total fixed-maturities available for sale
Amortized Cost
Amortized Cost	5,621,453	5,430,898
Fair Value
Fair Value	4,985,406	5,582,689
Fixed-maturities available for sale \| Loaned securities, amortized cost \| Total fixed-maturities available for sale
Amortized Cost
Less: loaned securities and securities sold under repurchase agreements	85,921	63,169
Fair Value
Less: loaned securities and securities sold under repurchase agreements	85,921	63,169
Fixed-maturities available for sale \| Loaned securities, fair value \| Total fixed-maturities available for sale
Amortized Cost
Less: loaned securities and securities sold under repurchase agreements	76,174	65,611
Fair Value
Less: loaned securities and securities sold under repurchase agreements	$ 76,174	$ 65,611

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