Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Amortized cost on fixed maturities trading investments	$ 4,574,492	$ 4,394,983
Cost - equity security trading investments	690,856	654,939
Cost - short-term investments	163,454	179,375
Reinsurance recoverable, allowance for credit losses	0	(12)
Fixed assets, accumulated depreciation	$ 330,764	$ 322,729
Common Stock
Common stock, shares authorized (in shares)	70,000,000	70,000,000
Common stock, shares issued (in shares)	55,371,000	55,371,000
Common stock, shares outstanding (in shares)	55,371,000	55,371,000