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
	Mar. 31, 2022	Mar. 31, 2021
Earnings
Net income	$ 445	$ 249
Less: Preferred stock dividends	5	5
Net income available to common stockholders	$ 440	$ 244
Shares
Weighted average common shares outstanding, basic	332.3	358.2
Dilutive effect of stock-based awards under compensation plans	5.0	4.0
Weighted average common shares outstanding and dilutive potential common shares	337.3	362.2
Earnings Per Share, Basic [Abstract]
Net income available to common stockholders	$ 1.32	$ 0.68
Earnings Per Share, Diluted [Abstract]
Net income available to common stockholders	$ 1.30	$ 0.67