Equity (Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ (30,920)
Income tax benefit (expense)	109,291	$ (110,262)
Ending Balance	(443,442)
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(18,085)	(20,007)
Change in OCI before reclassifications	(2,362)	2,666
Amounts reclassified from AOCI	0	0
Income tax benefit (expense)	212	(181)
Ending Balance	(20,235)	(17,522)
Net unrealized investment gains (losses)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(927,778)	(1,474,475)
Change in OCI before reclassifications	(297,240)	377,650
Amounts reclassified from AOCI	(16,067)	4,451
Income tax benefit (expense)	65,788	(80,219)
Ending Balance	(1,175,297)	(1,172,593)
Accumulated Other Comprehensive   Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(30,920)	(10,065)
Change in OCI before reclassifications	(505,746)	522,515
Amounts reclassified from AOCI	(16,067)	4,451
Income tax benefit (expense)	109,291	(110,262)
Ending Balance	(443,442)	406,639
Interest Rate Remeasurement of Future Policy Benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	71,195	119,368
Change in OCI before reclassifications	32,830	(38,224)
Amounts reclassified from AOCI	0	0
Income tax benefit (expense)	(6,894)	8,027
Ending Balance	97,131	89,171
Gain (Loss) from Changes in Non-Performance Risk on Market Risk Benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	843,748	1,365,049
Change in OCI before reclassifications	(238,974)	180,423
Amounts reclassified from AOCI	0	0
Income tax benefit (expense)	50,185	(37,889)
Ending Balance	654,959	1,507,583
Cash flow hedges | Net unrealized investment gains (losses)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	12,000	139,000
Ending Balance	$ 39,000	$ 118,000