Earnings Per Common Share - Computations of Diluted 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
Earnings Per Share [Abstract]
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
Adjusted 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)
Plus: Incremental shares from assumed conversion of stock-based compensation awards	896	661	743	605
Adjusted weighted-average shares outstanding (in shares)	167,567	166,570	167,437	167,093
Diluted earnings per common share (in USD per share)	$ 4.02	$ 3.98	$ 10.78	$ 13.05