Investments - Held-to-maturity Securities by Type and Tenor (Detail) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 51,662	$ 4,699
Fair Value	$ 50,260	$ 4,873
Weighted Average Yield	2.99%	2.13%
U.S. government obligations
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 51,499	$ 4,054
Fair Value	$ 50,100	$ 4,200
Weighted Average Yield	2.99%	2.30%
U.S. government obligations | Less than 1 year
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 5,319
Fair Value	$ 5,282
Weighted Average Yield	2.98%
U.S. government obligations | 1 year to 5 years
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 45,154	$ 4,054
Fair Value	$ 43,852	$ 4,200
Weighted Average Yield	3.00%	2.30%
U.S. government obligations | 5 years to 10 years
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 1,026
Fair Value	$ 966
Weighted Average Yield	2.89%
Securities backed by real estate
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 163	$ 645
Fair Value	$ 160	$ 673
Weighted Average Yield	3.24%	1.04%
Securities backed by real estate | 5 years to 10 years
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 2	$ 3
Fair Value	$ 2	$ 3
Weighted Average Yield	5.63%	2.78%
Securities backed by real estate | Greater than 10 years
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 161	$ 642
Fair Value	$ 158	$ 670
Weighted Average Yield	3.18%	1.03%