Accumulated Other Comprehensive Income - Components of and Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 9,257		$ 5,899	$ 3,960		$ 3,755
Other comprehensive income (loss) before reclassifications	1,311	$ 637	63	58	$ (210)	151
Amounts reclassified to (from) AOCI	2	4	0	(2)	8	20
Deferred income tax benefit (expense)	(277)	(137)	(13)	(11)	43	58
Ending balance	9,982	9,257		5,441	3,960
Total
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	445	(59)	(109)	(378)	(219)	(448)
Ending balance	1,481	445	(59)	(333)	(378)	(219)
Change in Net Unrealized Investment Gains (Losses)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	44	(343)	(299)	(598)	(382)	(722)
Other comprehensive income (loss) before reclassifications	1,689	489	(56)	(182)	(269)	261
Amounts reclassified to (from) AOCI	2	4	0	(2)	10	20
Deferred income tax benefit (expense)	(357)	(106)	12	52	43	59
Ending balance	1,378	44	(343)	(730)	(598)	(382)
Change in Discount Rate for Future Policy Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	287	207	105	210	147	253
Other comprehensive income (loss) before reclassifications	(290)	101	128	248	63	(106)
Amounts reclassified to (from) AOCI	0	0	0	0	0	0
Deferred income tax benefit (expense)	59	(21)	(26)	(66)	0	0
Ending balance	56	287	207	392	210	147
Change in Instrument- Specific Credit Risk for Market Risk Benefit
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	6	(8)	1	6	14	21
Other comprehensive income (loss) before reclassifications	(90)	18	(11)	(9)	(8)	(7)
Amounts reclassified to (from) AOCI	0	0	0	0	0	0
Deferred income tax benefit (expense)	19	(4)	2	3	0	0
Ending balance	(65)	6	(8)	0	6	14
Defined Benefit Pension Plan Adjustment
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	104	89	85	5	3	1
Other comprehensive income (loss) before reclassifications	4	19	5	1	4	3
Amounts reclassified to (from) AOCI	0	0	0	0	(2)	0
Deferred income tax benefit (expense)	(1)	(4)	(1)	0	0	(1)
Ending balance	107	104	89	6	5	3
Foreign Currency Translation / Other
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	4	(4)	(1)	(1)	(1)	(1)
Other comprehensive income (loss) before reclassifications	(2)	10	(3)	0	0	0
Amounts reclassified to (from) AOCI	0	0	0	0	0	0
Deferred income tax benefit (expense)	3	(2)	0	0	0	0
Ending balance	$ 5	$ 4	$ (4)	$ (1)	$ (1)	$ (1)