Equity (Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands		3 Months Ended			9 Months Ended
		Sep. 30, 2023	Sep. 30, 2022		Sep. 30, 2023	Sep. 30, 2022
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	[1]				$ (10,065)
Income tax benefit (expense)		$ 201,437	$ 146,711	[2]	194,021	$ 100,893	[2]
Ending Balance		(739,599)			(739,599)
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance					(20,007)	(11,274)
Change in OCI before reclassifications					431	(11,519)
Amounts reclassified from AOCI					0	0
Income tax benefit (expense)					(51)	1,357
Ending Balance		(19,627)	(21,436)		(19,627)	(21,436)
Net unrealized investment gains (losses)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance					(1,474,475)	306,331
Change in OCI before reclassifications					(482,272)	(2,552,163)
Amounts reclassified from AOCI					(17,746)	(55,886)
Income tax benefit (expense)					105,037	547,513
Ending Balance		(1,869,456)	(1,754,205)		(1,869,456)	(1,754,205)
Accumulated Other Comprehensive   Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance					(10,065)	396,454
Change in OCI before reclassifications					(905,809)	(430,464)
Amounts reclassified from AOCI					(17,746)	(55,886)
Income tax benefit (expense)					194,021	100,893
Ending Balance		(739,599)	10,997		(739,599)	10,997
Interest Rate Remeasurement of Future Policy Benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance					119,368	(125,809)
Change in OCI before reclassifications					73,321	346,865
Amounts reclassified from AOCI					0	0
Income tax benefit (expense)					(15,396)	(72,842)
Ending Balance		177,293	148,214		177,293	148,214
Gain (loss) from Changes in Non-Performance Risk on Market Risk Benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance					1,365,049	227,206
Change in OCI before reclassifications					(497,289)	1,786,353
Amounts reclassified from AOCI					0	0
Income tax benefit (expense)					104,431	(375,135)
Ending Balance		972,191	1,638,424		972,191	1,638,424
Cash flow hedges | Net unrealized investment gains (losses)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance					40,000	40,000
Ending Balance		$ 94,000	$ 228,000		$ 94,000	$ 228,000

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

[2] Prior period amounts adjusted for the implementation of ASU 2018-12: Targeted Improvements to the Accounting for Long-Duration Contracts.