Investments - Summary of Changes in Fair Value for Level 3 Investments (Detail) - Investments - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 16,109	$ 16,332	$ 13,902	$ 16,423
Net realized gains/(losses)	103	78	428	184
Net unrealized gains/(losses)	(407)	155	(1,828)	1,244
Purchases	445	496	1,385	1,467
Sales	(236)	(478)	(741)	(1,070)
Settlements	(272)	(831)	(1,461)	(2,421)
Transfers into level 3	1,687	806	6,425	1,843
Transfers out of level 3	(475)	(2,879)	(1,156)	(3,991)
Ending balance	16,954	13,679	16,954	13,679
Corporate debt securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	6,576	4,958	4,527	5,286
Net realized gains/(losses)	69	33	224	150
Net unrealized gains/(losses)	(111)	47	(297)	302
Purchases	137	101	624	374
Sales	(78)	(204)	(151)	(383)
Settlements	(143)	(601)	(810)	(1,254)
Transfers into level 3	659	529	2,944	1,120
Transfers out of level 3	(371)	(586)	(323)	(1,318)
Ending balance	6,738	4,277	6,738	4,277
Securities backed by real estate
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	1,067	1,117	1,078	998
Net realized gains/(losses)	7	12	21	29
Net unrealized gains/(losses)	(88)	(11)	(287)	25
Purchases	17	14	76	212
Sales	(47)	(19)	(96)	(43)
Settlements	(23)	(51)	(140)	(247)
Transfers into level 3	1	26	269	114
Transfers out of level 3	(22)	0	(9)	0
Ending balance	912	1,088	912	1,088
Other debt obligations
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	303	502	382	497
Net realized gains/(losses)	3	4	9	9
Net unrealized gains/(losses)	(3)	1	(8)	1
Purchases	4	10	28	32
Sales	0	(1)	0	(3)
Settlements	(23)	(33)	(127)	(54)
Transfers out of level 3	0	(96)	0	(95)
Ending balance	284	387	284	387
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	8,163	9,755	7,915	9,642
Net realized gains/(losses)	24	29	174	(4)
Net unrealized gains/(losses)	(205)	118	(1,236)	916
Purchases	287	371	657	849
Sales	(111)	(254)	(494)	(641)
Settlements	(83)	(146)	(384)	(866)
Transfers into level 3	1,027	251	3,212	609
Transfers out of level 3	(82)	(2,197)	(824)	(2,578)
Ending balance	$ 9,020	$ 7,927	$ 9,020	$ 7,927