Market Risk Benefits - Market Risk Benefits In Asset and Liability Positions (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022		Dec. 31, 2021	Jan. 01, 2021
Liability for Future Policy Benefit, Activity [Line Items]
Market risk benefit assets	$ 2,519,234	$ 1,306,000	$ 1,393,237	[1]
Market risk benefit liabilities	4,371,178	5,945,000	5,521,601	[1]
Variable Annuities
Liability for Future Policy Benefit, Activity [Line Items]
Net amount at risk	$ 12,504,440	$ 14,124,120
Weighted-average attained age of contractholders	70 years	69 years
Market risk benefit assets	$ 2,519,234	$ 1,306,404
Market risk benefit liabilities	4,371,178	5,945,122
Net liability	$ 1,851,944	$ 4,638,718	$ 4,550,625		$ 8,884,362	$ (12,032)

[1] Prior period amounts adjusted for the implementation of Accounting Standard Update ("ASU") 2018-12: Targeted Improvements to the Accounting for Long-Duration Contracts.