Investments - Contractual Maturities (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Amortized Cost
Amortized Cost	$ 5,737,089
Loaned securities	89,919	$ 112,139
Fixed-maturities available for sale, amortized cost	5,685,122	5,587,261
Fair Value
Fair Value	5,200,219
Loaned securities	89,919	112,139
Total fixed-maturities available for sale, Fair Value	5,155,897	5,017,711
Non asset-backed securities
Amortized Cost
Due in one year or less	111,170
Due after one year through five years	1,264,251
Due after five years through 10 years	957,240
Due after 10 years	894,764
Fair Value
Due in one year or less	109,354
Due after one year through five years	1,184,796
Due after five years through 10 years	844,337
Due after 10 years	722,676
Asset-backed and mortgage-backed securities
Amortized Cost
Asset-backed and mortgage-backed securities	2,509,664
Fair Value
Asset-backed and mortgage-backed securities	2,339,056
Total fixed-maturities available for sale
Amortized Cost
Fixed-maturities available for sale, amortized cost	5,685,122	5,587,261
Fair Value
Total fixed-maturities available for sale, Fair Value	5,155,897	$ 5,017,711
Loaned securities, amortized cost
Amortized Cost
Loaned securities	51,967
Fair Value
Loaned securities	51,967
Loaned securities, fair value
Amortized Cost
Loaned securities	44,322
Fair Value
Loaned securities	$ 44,322

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