Investments - Contractual Maturities (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Amortized Cost
Less: loaned securities	$ 95,286	$ 103,996
Total fixed-maturities available for sale	5,563,766	5,367,729
Fair Value
Less: loaned securities	95,286	103,996
Total fixed-maturities available for sale	5,401,704	5,517,078
Fixed-maturities available for sale \| Non asset-backed securities
Amortized Cost
Due in one year or less	177,655
Due after one year through five years	1,216,226
Due after five years through 10 years	1,124,190
Due after 10 years	842,494
Fair Value
Due in one year or less	177,609
Due after one year through five years	1,200,007
Due after five years through 10 years	1,071,396
Due after 10 years	798,365
Fixed-maturities available for sale \| Asset-backed and mortgage-backed securities
Amortized Cost
Asset-backed and mortgage-backed securities	2,263,775
Fair Value
Asset-backed and mortgage-backed securities	2,212,641
Fixed-maturities available for sale \| Total fixed-maturities available for sale
Amortized Cost
Total	5,624,340	5,430,898
Total fixed-maturities available for sale	5,563,766	5,367,729
Fair Value
Total	5,460,018	5,582,689
Total fixed-maturities available for sale	5,401,704	5,517,078
Fixed-maturities available for sale \| Loaned securities, amortized cost \| Total fixed-maturities available for sale
Amortized Cost
Less: loaned securities	60,574	63,169
Fair Value
Less: loaned securities	60,574	63,169
Fixed-maturities available for sale \| Loaned securities, fair value \| Total fixed-maturities available for sale
Amortized Cost
Less: loaned securities	58,314	65,611
Fair Value
Less: loaned securities	$ 58,314	$ 65,611

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