Investments - Available-for-Sale Securities by Tenor (Detail) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 52,746	$ 49,593
Fair Value	$ 49,234	$ 48,932
Weighted Average Yield	0.68%	0.52%
U.S.
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 50,120	$ 46,900
Fair Value	$ 47,055	$ 46,322
Weighted Average Yield	0.69%	0.53%
Non-U.S.
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 2,626	$ 2,693
Fair Value	$ 2,179	$ 2,610
Weighted Average Yield	0.40%	0.33%
Less than 1 year | U.S.
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 8,103	$ 25
Fair Value	$ 7,861	$ 25
Weighted Average Yield	0.37%	0.12%
1 year to 5 years | U.S.
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 41,479	$ 41,536
Fair Value	$ 38,706	$ 41,066
Weighted Average Yield	0.74%	0.47%
1 year to 5 years | Non-U.S.
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 10
Fair Value	$ 10
Weighted Average Yield	0.27%
5 years to 10 years | U.S.
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 538	$ 5,337
Fair Value	$ 488	$ 5,229
Weighted Average Yield	1.86%	0.92%
5 years to 10 years | Non-U.S.
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 2,616	$ 2,693
Fair Value	$ 2,169	$ 2,610
Weighted Average Yield	0.40%	0.33%
Greater than 10 years | U.S.
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		$ 2
Fair Value		$ 2
Weighted Average Yield		2.00%