Market Risk Benefits - Market Risk Benefits In Asset and Liability Positions (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Liability for Future Policy Benefit, Activity [Line Items]
Total market risk benefit assets	$ 2,536,843	$ 1,427,000	$ 2,367,243
Total market risk benefit liabilities	4,388,317	5,622,000	5,144,401
Variable Annuities
Liability for Future Policy Benefit, Activity [Line Items]
Net amount at risk	$ 8,350,431	$ 10,414,717
Weighted-average attained age of contractholders	70 years	69 years
Direct and assumed	$ 1,472,957	$ 880,131
Ceded	1,063,886	547,357
Total market risk benefit assets	2,536,843	1,427,488
Direct and assumed	4,088,679	5,498,342
Ceded	299,638	123,339
Total market risk benefit liabilities	4,388,317	5,621,681
Net liability	$ 1,851,474	$ 4,194,193	$ 3,694,950	$ 4,550,625