Investments - Contractual Maturities (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Amortized Cost
Less: loaned securities	$ 148,098	$ 203,693
Fixed-maturities available for sale, amortized cost	5,648,303	5,599,111
Fair Value
Less: loaned securities	148,098	203,693
Total fixed-maturities available for sale, Fair Value	5,176,521	5,188,228
Non asset-backed securities
Amortized Cost
Due in one year or less	93,971
Due after one year through five years	1,159,906
Due after five years through 10 years	980,900
Due after 10 years	906,047
Fair Value
Due in one year or less	92,593
Due after one year through five years	1,105,988
Due after five years through 10 years	890,580
Due after 10 years	711,395
Asset-backed and mortgage-backed securities
Amortized Cost
Asset-backed and mortgage-backed securities	2,617,499
Fair Value
Asset-backed and mortgage-backed securities	2,479,685
Total fixed-maturities available for sale
Amortized Cost
Total	5,758,323	5,734,767
Fixed-maturities available for sale, amortized cost	5,648,303	5,599,111
Fair Value
Total	5,280,241	5,315,410
Total fixed-maturities available for sale, Fair Value	5,176,521	5,188,228
Fixed-maturities available for sale \| Total fixed-maturities available for sale
Amortized Cost
Total	5,758,323
Fixed-maturities available for sale, amortized cost	5,648,303
Fair Value
Total	5,280,241
Total fixed-maturities available for sale, Fair Value	5,176,521
Loaned securities, amortized cost \| Total fixed-maturities available for sale
Amortized Cost
Less: loaned securities	110,020	135,656
Fair Value
Less: loaned securities	110,020	135,656
Loaned securities, fair value \| Total fixed-maturities available for sale
Amortized Cost
Less: loaned securities	103,720	127,182
Fair Value
Less: loaned securities	$ 103,720	$ 127,182

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