Gross Unrealized Losses and Fair Value of Corporate Securities Based on Industries (Detail) $ in Millions	Jun. 30, 2022 USD ($) Securities	Dec. 31, 2021 USD ($) Securities
Available for Sale Securities Continuous Unrealized Loss Position [Line Items]
Less than 12 months, Fair value	$ 30,227	$ 4,991
Less than 12 months, Gross unrealized losses	$ (3,039)	$ (110)
Less than 12 months, Number of securities in a continuous loss position | Securities	4,016	635
12 months or more, Fair value	$ 1,102	$ 308
12 months or more, Gross unrealized losses	$ (266)	$ (25)
12 months or more, Number of securities in a continuous loss position | Securities	157	35
Fair value	$ 31,329	$ 5,299
Gross unrealized losses	$ (3,305)	$ (135)
Number of securities in a continuous loss position | Securities	4,173	670
Fixed maturity securities
Available for Sale Securities Continuous Unrealized Loss Position [Line Items]
Less than 12 months, Fair value	$ 30,227	$ 4,991
Less than 12 months, Gross unrealized losses	$ (3,039)	$ (110)
Less than 12 months, Number of securities in a continuous loss position | Securities	4,016	635
12 months or more, Fair value	$ 1,102	$ 308
12 months or more, Gross unrealized losses	$ (266)	$ (25)
12 months or more, Number of securities in a continuous loss position | Securities	157	35
Fair value	$ 31,329	$ 5,299
Gross unrealized losses	$ (3,305)	$ (135)
Number of securities in a continuous loss position | Securities	4,173	670
Fixed maturity securities | U.S. corporate
Available for Sale Securities Continuous Unrealized Loss Position [Line Items]
Less than 12 months, Fair value	$ 17,949	$ 2,593
Less than 12 months, Gross unrealized losses	$ (1,896)	$ (64)
Less than 12 months, Number of securities in a continuous loss position | Securities	2,235	266
12 months or more, Fair value	$ 622	$ 196
12 months or more, Gross unrealized losses	$ (160)	$ (15)
12 months or more, Number of securities in a continuous loss position | Securities	72	22
Fair value	$ 18,571	$ 2,789
Gross unrealized losses	$ (2,056)	$ (79)
Number of securities in a continuous loss position | Securities	2,307	288
Fixed maturity securities | U.S. corporate | Utilities
Available for Sale Securities Continuous Unrealized Loss Position [Line Items]
Less than 12 months, Fair value	$ 2,176	$ 211
Less than 12 months, Gross unrealized losses	$ (268)	$ (7)
Less than 12 months, Number of securities in a continuous loss position | Securities	301	32
12 months or more, Fair value	$ 56	$ 29
12 months or more, Gross unrealized losses	$ (17)	$ (2)
12 months or more, Number of securities in a continuous loss position | Securities	15	7
Fair value	$ 2,232	$ 240
Gross unrealized losses	$ (285)	$ (9)
Number of securities in a continuous loss position | Securities	316	39
Fixed maturity securities | U.S. corporate | Energy
Available for Sale Securities Continuous Unrealized Loss Position [Line Items]
Less than 12 months, Fair value	$ 1,534	$ 166
Less than 12 months, Gross unrealized losses	$ (162)	$ (3)
Less than 12 months, Number of securities in a continuous loss position | Securities	205	18
12 months or more, Fair value	$ 53	$ 25
12 months or more, Gross unrealized losses	$ (11)	$ (7)
12 months or more, Number of securities in a continuous loss position | Securities	6	4
Fair value	$ 1,587	$ 191
Gross unrealized losses	$ (173)	$ (10)
Number of securities in a continuous loss position | Securities	211	22
Fixed maturity securities | U.S. corporate | Finance and insurance
Available for Sale Securities Continuous Unrealized Loss Position [Line Items]
Less than 12 months, Fair value	$ 5,276	$ 960
Less than 12 months, Gross unrealized losses	$ (554)	$ (22)
Less than 12 months, Number of securities in a continuous loss position | Securities	637	89
12 months or more, Fair value	$ 183	$ 62
12 months or more, Gross unrealized losses	$ (50)	$ (2)
12 months or more, Number of securities in a continuous loss position | Securities	17	3
Fair value	$ 5,459	$ 1,022
Gross unrealized losses	$ (604)	$ (24)
Number of securities in a continuous loss position | Securities	654	92
Fixed maturity securities | U.S. corporate | Consumer-non-cyclical
Available for Sale Securities Continuous Unrealized Loss Position [Line Items]
Less than 12 months, Fair value	$ 2,657	$ 296
Less than 12 months, Gross unrealized losses	$ (268)	$ (7)
Less than 12 months, Number of securities in a continuous loss position | Securities	284	30
12 months or more, Fair value	$ 76	$ 14
12 months or more, Gross unrealized losses	$ (24)	$ (1)
12 months or more, Number of securities in a continuous loss position | Securities	7	2
Fair value	$ 2,733	$ 310
Gross unrealized losses	$ (292)	$ (8)
Number of securities in a continuous loss position | Securities	291	32
Fixed maturity securities | U.S. corporate | Technology and communications
Available for Sale Securities Continuous Unrealized Loss Position [Line Items]
Less than 12 months, Fair value	$ 2,192	$ 378
Less than 12 months, Gross unrealized losses	$ (227)	$ (12)
Less than 12 months, Number of securities in a continuous loss position | Securities	282	37
12 months or more, Fair value	$ 123	$ 29
12 months or more, Gross unrealized losses	$ (33)	$ (1)
12 months or more, Number of securities in a continuous loss position | Securities	11	2
Fair value	$ 2,315	$ 407
Gross unrealized losses	$ (260)	$ (13)
Number of securities in a continuous loss position | Securities	293	39
Fixed maturity securities | U.S. corporate | Industrial
Available for Sale Securities Continuous Unrealized Loss Position [Line Items]
Less than 12 months, Fair value	$ 805	$ 143
Less than 12 months, Gross unrealized losses	$ (96)	$ (3)
Less than 12 months, Number of securities in a continuous loss position | Securities	101	18
12 months or more, Fair value	$ 11	$ 0
12 months or more, Gross unrealized losses	$ (2)	$ 0
12 months or more, Number of securities in a continuous loss position | Securities	1	0
Fair value	$ 816	$ 143
Gross unrealized losses	$ (98)	$ (3)
Number of securities in a continuous loss position | Securities	102	18
Fixed maturity securities | U.S. corporate | Capital goods
Available for Sale Securities Continuous Unrealized Loss Position [Line Items]
Less than 12 months, Fair value	$ 1,340	$ 171
Less than 12 months, Gross unrealized losses	$ (138)	$ (3)
Less than 12 months, Number of securities in a continuous loss position | Securities	162	16
12 months or more, Fair value	$ 24	$ 18
12 months or more, Gross unrealized losses	$ (7)	$ (1)
12 months or more, Number of securities in a continuous loss position | Securities	4	2
Fair value	$ 1,364	$ 189
Gross unrealized losses	$ (145)	$ (4)
Number of securities in a continuous loss position | Securities	166	18
Fixed maturity securities | U.S. corporate | Consumer-cyclical
Available for Sale Securities Continuous Unrealized Loss Position [Line Items]
Less than 12 months, Fair value	$ 1,107	$ 268
Less than 12 months, Gross unrealized losses	$ (111)	$ (7)
Less than 12 months, Number of securities in a continuous loss position | Securities	156	26
12 months or more, Fair value	$ 73	$ 0
12 months or more, Gross unrealized losses	$ (14)	$ 0
12 months or more, Number of securities in a continuous loss position | Securities	7	0
Fair value	$ 1,180	$ 268
Gross unrealized losses	$ (125)	$ (7)
Number of securities in a continuous loss position | Securities	163	26
Fixed maturity securities | U.S. corporate | Transportation
Available for Sale Securities Continuous Unrealized Loss Position [Line Items]
Less than 12 months, Fair value	$ 716
Less than 12 months, Gross unrealized losses	$ (60)
Less than 12 months, Number of securities in a continuous loss position | Securities	87
12 months or more, Fair value	$ 5
12 months or more, Gross unrealized losses	$ (1)
12 months or more, Number of securities in a continuous loss position | Securities	2
Fair value	$ 721
Gross unrealized losses	$ (61)
Number of securities in a continuous loss position | Securities	89
Fixed maturity securities | U.S. corporate | Other
Available for Sale Securities Continuous Unrealized Loss Position [Line Items]
Less than 12 months, Fair value	$ 146	$ 0
Less than 12 months, Gross unrealized losses	$ (12)	$ 0
Less than 12 months, Number of securities in a continuous loss position | Securities	20	0
12 months or more, Fair value	$ 18	$ 19
12 months or more, Gross unrealized losses	$ (1)	$ (1)
12 months or more, Number of securities in a continuous loss position | Securities	2	2
Fair value	$ 164	$ 19
Gross unrealized losses	$ (13)	$ (1)
Number of securities in a continuous loss position | Securities	22	2
Fixed maturity securities | Non-U.S. corporate
Available for Sale Securities Continuous Unrealized Loss Position [Line Items]
Less than 12 months, Fair value	$ 5,407	$ 912
Less than 12 months, Gross unrealized losses	$ (558)	$ (21)
Less than 12 months, Number of securities in a continuous loss position | Securities	691	124
12 months or more, Fair value	$ 248	$ 62
12 months or more, Gross unrealized losses	$ (66)	$ (5)
12 months or more, Number of securities in a continuous loss position | Securities	35	8
Fair value	$ 5,655	$ 974
Gross unrealized losses	$ (624)	$ (26)
Number of securities in a continuous loss position | Securities	726	132
Fixed maturity securities | Non-U.S. corporate | Utilities
Available for Sale Securities Continuous Unrealized Loss Position [Line Items]
Less than 12 months, Fair value	$ 596	$ 69
Less than 12 months, Gross unrealized losses	$ (51)	$ (2)
Less than 12 months, Number of securities in a continuous loss position | Securities	63	9
12 months or more, Fair value	$ 21	$ 0
12 months or more, Gross unrealized losses	$ (6)	$ 0
12 months or more, Number of securities in a continuous loss position | Securities	3	0
Fair value	$ 617	$ 69
Gross unrealized losses	$ (57)	$ (2)
Number of securities in a continuous loss position | Securities	66	9
Fixed maturity securities | Non-U.S. corporate | Energy
Available for Sale Securities Continuous Unrealized Loss Position [Line Items]
Less than 12 months, Fair value	$ 608	$ 64
Less than 12 months, Gross unrealized losses	$ (61)	$ (1)
Less than 12 months, Number of securities in a continuous loss position | Securities	65	10
12 months or more, Fair value	$ 4	$ 0
12 months or more, Gross unrealized losses	$ (1)	$ 0
12 months or more, Number of securities in a continuous loss position | Securities	1	0
Fair value	$ 612	$ 64
Gross unrealized losses	$ (62)	$ (1)
Number of securities in a continuous loss position | Securities	66	10
Fixed maturity securities | Non-U.S. corporate | Finance and insurance
Available for Sale Securities Continuous Unrealized Loss Position [Line Items]
Less than 12 months, Fair value	$ 1,282	$ 366
Less than 12 months, Gross unrealized losses	$ (117)	$ (8)
Less than 12 months, Number of securities in a continuous loss position | Securities	190	43
12 months or more, Fair value	$ 144	$ 18
12 months or more, Gross unrealized losses	$ (36)	$ (1)
12 months or more, Number of securities in a continuous loss position | Securities	16	2
Fair value	$ 1,426	$ 384
Gross unrealized losses	$ (153)	$ (9)
Number of securities in a continuous loss position | Securities	206	45
Fixed maturity securities | Non-U.S. corporate | Consumer-non-cyclical
Available for Sale Securities Continuous Unrealized Loss Position [Line Items]
Less than 12 months, Fair value	$ 480	$ 67
Less than 12 months, Gross unrealized losses	$ (61)	$ (1)
Less than 12 months, Number of securities in a continuous loss position | Securities	51	12
12 months or more, Fair value	$ 8	$ 6
12 months or more, Gross unrealized losses	$ (3)	$ (1)
12 months or more, Number of securities in a continuous loss position | Securities	4	1
Fair value	$ 488	$ 73
Gross unrealized losses	$ (64)	$ (2)
Number of securities in a continuous loss position | Securities	55	13
Fixed maturity securities | Non-U.S. corporate | Technology and communications
Available for Sale Securities Continuous Unrealized Loss Position [Line Items]
Less than 12 months, Fair value	$ 704	$ 48
Less than 12 months, Gross unrealized losses	$ (74)	$ (1)
Less than 12 months, Number of securities in a continuous loss position | Securities	83	8
12 months or more, Fair value	$ 0	$ 0
12 months or more, Gross unrealized losses	$ 0	$ 0
12 months or more, Number of securities in a continuous loss position | Securities	0	0
Fair value	$ 704	$ 48
Gross unrealized losses	$ (74)	$ (1)
Number of securities in a continuous loss position | Securities	83	8
Fixed maturity securities | Non-U.S. corporate | Industrial
Available for Sale Securities Continuous Unrealized Loss Position [Line Items]
Less than 12 months, Fair value	$ 475	$ 122
Less than 12 months, Gross unrealized losses	$ (58)	$ (3)
Less than 12 months, Number of securities in a continuous loss position | Securities	68	14
12 months or more, Fair value	$ 16	$ 0
12 months or more, Gross unrealized losses	$ (5)	$ 0
12 months or more, Number of securities in a continuous loss position | Securities	2	0
Fair value	$ 491	$ 122
Gross unrealized losses	$ (63)	$ (3)
Number of securities in a continuous loss position | Securities	70	14
Fixed maturity securities | Non-U.S. corporate | Capital goods
Available for Sale Securities Continuous Unrealized Loss Position [Line Items]
Less than 12 months, Fair value	$ 428	$ 78
Less than 12 months, Gross unrealized losses	$ (50)	$ (1)
Less than 12 months, Number of securities in a continuous loss position | Securities	54	8
12 months or more, Fair value	$ 0	$ 0
12 months or more, Gross unrealized losses	$ 0	$ 0
12 months or more, Number of securities in a continuous loss position | Securities	0	0
Fair value	$ 428	$ 78
Gross unrealized losses	$ (50)	$ (1)
Number of securities in a continuous loss position | Securities	54	8
Fixed maturity securities | Non-U.S. corporate | Consumer-cyclical
Available for Sale Securities Continuous Unrealized Loss Position [Line Items]
Less than 12 months, Fair value	$ 236	$ 22
Less than 12 months, Gross unrealized losses	$ (26)	$ (1)
Less than 12 months, Number of securities in a continuous loss position | Securities	38	8
12 months or more, Fair value	$ 19	$ 15
12 months or more, Gross unrealized losses	$ (3)	$ (1)
12 months or more, Number of securities in a continuous loss position | Securities	4	3
Fair value	$ 255	$ 37
Gross unrealized losses	$ (29)	$ (2)
Number of securities in a continuous loss position | Securities	42	11
Fixed maturity securities | Non-U.S. corporate | Transportation
Available for Sale Securities Continuous Unrealized Loss Position [Line Items]
Less than 12 months, Fair value	$ 195	$ 37
Less than 12 months, Gross unrealized losses	$ (22)	$ (1)
Less than 12 months, Number of securities in a continuous loss position | Securities	25	7
12 months or more, Fair value	$ 0	$ 0
12 months or more, Gross unrealized losses	$ 0	$ 0
12 months or more, Number of securities in a continuous loss position | Securities	0	0
Fair value	$ 195	$ 37
Gross unrealized losses	$ (22)	$ (1)
Number of securities in a continuous loss position | Securities	25	7
Fixed maturity securities | Non-U.S. corporate | Other
Available for Sale Securities Continuous Unrealized Loss Position [Line Items]
Less than 12 months, Fair value	$ 403	$ 39
Less than 12 months, Gross unrealized losses	$ (38)	$ (2)
Less than 12 months, Number of securities in a continuous loss position | Securities	54	5
12 months or more, Fair value	$ 36	$ 23
12 months or more, Gross unrealized losses	$ (12)	$ (2)
12 months or more, Number of securities in a continuous loss position | Securities	5	2
Fair value	$ 439	$ 62
Gross unrealized losses	$ (50)	$ (4)
Number of securities in a continuous loss position | Securities	59	7
Fixed maturity securities | Corporate Debt Securities
Available for Sale Securities Continuous Unrealized Loss Position [Line Items]
Less than 12 months, Fair value	$ 23,356	$ 3,505
Less than 12 months, Gross unrealized losses	$ (2,454)	$ (85)
Less than 12 months, Number of securities in a continuous loss position | Securities	2,926	390
12 months or more, Fair value	$ 870	$ 258
12 months or more, Gross unrealized losses	$ (226)	$ (20)
12 months or more, Number of securities in a continuous loss position | Securities	107	30
Fair value	$ 24,226	$ 3,763
Gross unrealized losses	$ (2,680)	$ (105)
Number of securities in a continuous loss position | Securities	3,033	420