Earnings Per Common Share - Computations of Basic Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Income available to common shareholders:
Net income	$ 721	$ 690	$ 1,907	$ 2,259
Less: Preferred stock dividends	(47)	(25)	(99)	(75)
Net income available to common equity	674	665	1,808	2,184
Less: Income attributable to unvested stock-based compensation awards	0	(1)	(3)	(4)
Net income available to common shareholders	$ 674	$ 664	$ 1,805	$ 2,180
Weighted-average shares outstanding:
Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards	167,011	166,217	167,010	166,787
Less: Unvested stock-based compensation awards	(340)	(308)	(316)	(299)
Weighted-average shares outstanding (in shares)	166,671	165,909	166,694	166,488
Basic earnings per common share (in USD per share)	$ 4.04	$ 4.00	$ 10.83	$ 13.09