Equity (Net Unrealized Investment Gains (Losses) in AOCI on AFS Fixed Maturity Securities with OTTI, Allowance for Credit Losses and All Other Investments (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022		Dec. 31, 2021
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	[1]	$ (10,065)
Ending balance		(30,920)	$ (10,065)	[1]
Accumulated Other Comprehensive Income (Loss) Related to Net Unrealized Investment Gains (Losses)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(1,474,475)	306,331		$ 553,925
Cumulative effect of adoption of ASU 2018-12					(81,364)
Ending balance		(927,778)	(1,474,475)		306,331
Net Unrealized Investment Gains (losses) | Accumulated Net Unrealized Investment Gains (Losses) Pre-Tax with Allowance
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		4,371	3,685		0
Cumulative effect of adoption of ASU 2018-12					0
Net unrealized investment gains (losses) on investments arising during period		(4,482)	(149)		2,951
Reclassification adjustment for (gains) losses included in net income		(265)	831		(8)
Reclassification due to allowance for credit losses recorded during the period		2,363	4		742
Impact of net unrealized investment (gains) losses		0	0		0
Ending balance		1,987	4,371		3,685
Net Unrealized Investment Gains (losses) | Accumulated Net Unrealized Investment Gains (Losses) Pre Tax All Other
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(2,161,026)	581,718		849,349
Cumulative effect of adoption of ASU 2018-12					(1,000)
Net unrealized investment gains (losses) on investments arising during period		744,727	(2,737,481)		(240,903)
Reclassification adjustment for (gains) losses included in net income		14,482	(5,259)		(24,986)
Reclassification due to allowance for credit losses recorded during the period		(2,363)	(4)		(742)
Impact of net unrealized investment (gains) losses		0	0		0
Ending balance		(1,404,180)	(2,161,026)		581,718
Net Unrealized Investment Gains (losses) | Deferred Policy Acquisition Costs and Other Costs
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(1,198,422)	835,430		1,200,048
Cumulative effect of adoption of ASU 2018-12					(89,160)
Net unrealized investment gains (losses) on investments arising during period		0	0		0
Reclassification adjustment for (gains) losses included in net income		0	0		0
Reclassification due to allowance for credit losses recorded during the period		0	0		0
Impact of net unrealized investment (gains) losses		397,071	(2,033,852)		(275,458)
Ending balance		(801,351)	(1,198,422)		835,430
Net Unrealized Investment Gains (losses) | Future Policy Benefits and Policyholders' Account Balances and Other Liabilities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		1,488,679	(1,033,194)		(1,348,231)
Cumulative effect of adoption of ASU 2018-12					(12,880)
Net unrealized investment gains (losses) on investments arising during period		0	0		0
Reclassification adjustment for (gains) losses included in net income		0	0		0
Reclassification due to allowance for credit losses recorded during the period		0	0		0
Impact of net unrealized investment (gains) losses		(459,581)	2,521,873		327,917
Ending balance		1,029,098	1,488,679		(1,033,194)
Net Unrealized Investment Gains (losses) | Income Tax Benefit (Expense)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		391,923	(81,308)		(147,241)
Cumulative effect of adoption of ASU 2018-12					21,677
Net unrealized investment gains (losses) on investments arising during period		(155,393)	574,760		50,016
Reclassification adjustment for (gains) losses included in net income		(2,984)	930		5,254
Reclassification due to allowance for credit losses recorded during the period		0	0		0
Impact of net unrealized investment (gains) losses		13,122	(102,459)		(11,014)
Ending balance		246,668	391,923		(81,308)
Net Unrealized Investment Gains (losses) | Accumulated Other Comprehensive Income (Loss) Related to Net Unrealized Investment Gains (Losses)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(1,474,475)	306,331		553,925
Cumulative effect of adoption of ASU 2018-12					(81,363)
Net unrealized investment gains (losses) on investments arising during period		584,852	(2,162,870)		(187,936)
Reclassification adjustment for (gains) losses included in net income		11,233	(3,498)		(19,740)
Reclassification due to allowance for credit losses recorded during the period		0	0		0
Impact of net unrealized investment (gains) losses		(49,388)	385,562		41,445
Ending balance		$ (927,778)	$ (1,474,475)		$ 306,331

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