Investments - Consolidated Investments (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Available-for-sale securities
Amortized Cost	$ 43,601	$ 35,723
Allowance for Expected Credit Losses	(35)	(31)	$ (8)	$ (10)
Gross Unrealized Gains	444	96
Gross Unrealized Losses	(3,591)	(4,570)
Fair Value/Carrying Value	40,419	31,218
Asset-backed securities
Available-for-sale securities
Amortized Cost	14,623	12,209
Allowance for Expected Credit Losses	(11)	(8)	(3)	0
Gross Unrealized Gains	191	36
Gross Unrealized Losses	(469)	(770)
Fair Value/Carrying Value	14,334	11,467
Commercial mortgage-backed securities
Available-for-sale securities
Amortized Cost	4,732	3,309
Allowance for Expected Credit Losses	(22)	(1)	(2)	0
Gross Unrealized Gains	23	12
Gross Unrealized Losses	(323)	(284)
Fair Value/Carrying Value	4,410	3,036
Corporates
Available-for-sale securities
Amortized Cost	18,780	15,879
Allowance for Expected Credit Losses	0	(15)	0	(7)
Gross Unrealized Gains	178	30
Gross Unrealized Losses	(2,379)	(2,995)
Fair Value/Carrying Value	16,579	12,899
Hybrids
Available-for-sale securities
Amortized Cost	668	781
Allowance for Expected Credit Losses	0	0
Gross Unrealized Gains	3	8
Gross Unrealized Losses	(53)	(84)
Fair Value/Carrying Value	618	705
Municipals
Available-for-sale securities
Amortized Cost	1,776	1,695
Allowance for Expected Credit Losses	0	0
Gross Unrealized Gains	14	4
Gross Unrealized Losses	(223)	(289)
Fair Value/Carrying Value	1,567	1,410
Residential mortgage-backed securities
Available-for-sale securities
Amortized Cost	2,501	1,631
Allowance for Expected Credit Losses	(2)	(7)	$ (3)	$ (3)
Gross Unrealized Gains	29	6
Gross Unrealized Losses	(104)	(109)
Fair Value/Carrying Value	2,424	1,521
U.S. Government
Available-for-sale securities
Amortized Cost	258	34
Allowance for Expected Credit Losses	0	0
Gross Unrealized Gains	4	0
Gross Unrealized Losses	(1)	(2)
Fair Value/Carrying Value	261	32
Foreign Governments
Available-for-sale securities
Amortized Cost	263	185
Allowance for Expected Credit Losses	0	0
Gross Unrealized Gains	2	0
Gross Unrealized Losses	(39)	(37)
Fair Value/Carrying Value	$ 226	$ 148

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
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