Investments - Schedule of Fixed Maturities by Contractual Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Amortized Cost, net
Due in one year or less	$ 117,643
Due after one year through five years	767,696
Due after five years through ten years	1,925,094
Due after ten years through twenty years	8,804,536
Due after twenty years	7,221,009
Mortgage-backed and asset-backed securities	128,034
Fixed maturities, net of allowance for credit losses	18,964,012
Fair Value
Due in one year or less	117,820
Due after one year through five years	787,970
Due after five years through ten years	1,963,237
Due after ten years through twenty years	8,303,529
Due after twenty years	6,200,565
Mortgage-backed and asset-backed securities	131,846
Fixed maturities, fair value	$ 17,504,967	$ 17,155,012