Earnings (Loss) Per Common Share - Computation of Basic and Diluted Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Earnings
Net income	$ 339	$ 482	$ 1,226	$ 1,636
Less: Preferred stock dividends	6	6	16	16
Net income available to common stockholders	$ 333	$ 476	$ 1,210	$ 1,620
Shares
Weighted average common shares outstanding, basic	322.1	345.6	327.3	352.5
Dilutive effect of stock-based awards under compensation plans	4.2	5.1	4.5	4.7
Weighted average common shares outstanding and dilutive potential common shares	326.3	350.7	331.8	357.2
Earnings Per Share, Basic [Abstract]
Net income available to common stockholders	$ 1.03	$ 1.38	$ 3.70	$ 4.60
Earnings Per Share, Diluted [Abstract]
Net income available to common stockholders	$ 1.02	$ 1.36	$ 3.65	$ 4.54