Investments - Investments Accounted for at Fair Value (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	$ 77,580		$ 77,580		$ 83,427
Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in funds at NAV	2,971		2,971		3,469
Investment at fair value	74,609		74,609		79,958
Transfers into level 3	1,687	$ 806	6,425	$ 1,843
Sales	(236)	(478)	(741)	(1,070)
Settlements	(272)	(831)	(1,461)	(2,421)
Level 1 | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	50,275		50,275		51,175
Level 2 | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	7,380		7,380		14,881
Level 3 | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	16,954		16,954		13,902
U.S. | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	46,196		46,196		46,322
U.S. | Level 1 | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	46,196		46,196		46,322
U.S. | Level 2 | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	0		0		0
U.S. | Level 3 | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	0		0		0
Non-U.S. | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	1,941		1,941		2,612
Non-U.S. | Level 1 | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	1,921		1,921		2,612
Non-U.S. | Level 2 | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	20		20		0
Non-U.S. | Level 3 | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	0		0		0
Corporate debt securities | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	9,828		9,828		9,793
Transfers into level 3	659	529	2,944	1,120
Sales	(78)	(204)	(151)	(383)
Settlements	(143)	(601)	(810)	(1,254)
Corporate debt securities | Level 1 | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	160		160		65
Corporate debt securities | Level 2 | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	2,930		2,930		5,201
Corporate debt securities | Level 3 | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	6,738		6,738		4,527
Securities backed by real estate | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	1,316		1,316		2,280
Transfers into level 3	1	26	269	114
Sales	(47)	(19)	(96)	(43)
Settlements	(23)	(51)	(140)	(247)
Securities backed by real estate | Level 1 | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	0		0		0
Securities backed by real estate | Level 2 | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	404		404		1,202
Securities backed by real estate | Level 3 | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	912		912		1,078
Money market instruments | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	1,002		1,002		1,396
Money market instruments | Level 1 | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	24		24		41
Money market instruments | Level 2 | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	978		978		1,355
Money market instruments | Level 3 | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	0		0		0
Other debt obligations | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	292		292		417
Sales	0	(1)	0	(3)
Settlements	(23)	(33)	(127)	(54)
Other debt obligations | Level 1 | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	0		0		0
Other debt obligations | Level 2 | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	8		8		35
Other debt obligations | Level 3 | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	284		284		382
Equity securities | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	14,034		14,034		17,138
Transfers into level 3	1,027	251	3,212	609
Sales	(111)	(254)	(494)	(641)
Settlements	(83)	$ (146)	(384)	$ (866)
Equity securities | Level 1 | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	1,974		1,974		2,135
Equity securities | Level 2 | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	3,040		3,040		7,088
Equity securities | Level 3 | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment at fair value	$ 9,020		$ 9,020		$ 7,915