Liability For Future Policy Benefits (Additional Insurance Reserves) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Dec. 31, 2021
Insurance [Abstract]
Balance, including amounts in AOCI, post-flooring	$ 12,664,445	$ 11,660,527
Flooring impact and amounts in AOCI	1,269,237	(896,930)
Balance, excluding amounts in AOCI, beginning of period, pre-flooring	13,933,682	10,763,597
Effect of assumption update			$ 22,910	$ 2,197,592
Effect of actual variances from expected experience and other activity			(12,611)	(215,658)
Adjusted balance, beginning of period			$ 13,943,981	$ 12,745,531
Assessments collected	828,657	738,061
Interest accrual	360,309	318,069
Benefits paid	(219,784)	(131,667)
Balance, excluding amounts in AOCI, end of period, pre-flooring	14,913,163	13,669,994
Flooring impact and amounts in AOCI	(1,714,686)	(1,576,731)
Balance after Transition	13,198,477	12,093,263
Amounts related to unrealized investment gains and losses after transition	12,979,687	11,902,756
Additional Liability, Long-Duration Insurance, after Reinsurance	218,790	190,507
Gross assessments	$ 1,168,206	$ 1,020,763
Weighted-average duration of the liability in years (at original discount rate)	22 years	23 years
Weighted-average interest rate (at original discount rate)	3.36%	3.38%