Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2022	Jun. 30, 2021
Earnings Per Share [Abstract]
Net income	$ 747	$ 604	$ 763	$ 519	$ 1,351	$ 1,282
Preferred stock dividends	(35)		(34)		(55)	(64)
Dividends and undistributed earnings allocated to participating securities	0		(1)		(1)	(1)
Net income available to common shareholders, basic	712		728		1,295	1,217
Net income available to common shareholders, diluted	$ 712		$ 728		$ 1,295	$ 1,217
Basic average common shares (in shares)	367,375		345,889		366,961	348,303
Effect of dilutive securities: common stock options and common stock awards (in shares)	4,748		5,693		5,119	5,131
Diluted average common shares (in shares)	372,123		351,582		372,080	353,434
Anti-dilutive securities (in shares)	1,990		176		741	192
Earnings per common share, basic:
Basic (in USD per share)	$ 1.94		$ 2.11		$ 3.53	$ 3.49
Earnings per common share, diluted:
Diluted (in USD per share)	$ 1.91		$ 2.07		$ 3.48	$ 3.44