Consolidated Balance Sheet (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Available-for-sale securities, amortized cost	$ 28,416	$ 34,863
Held-to-maturity securities, fair value	$ 4,729	$ 884
Common stock, par value per share (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	1,100,000,000	1,100,000,000
Common stock, shares issued (in shares)	511,861,447	507,682,838
Common stock, shares outstanding (in shares)	302,459,258	299,324,357
Treasury stock, common, shares (in shares)	209,402,189	208,358,481