Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share [Abstract]
Net income from continuing operations	$ 5,725	$ 3,003	$ 4,591
Less: Net income attributable to noncontrolling interests	51	41	49
Preferred stock dividends	233	229	236
Preferred stock discount accretion and redemptions	5	4	4
Net income from continuing operations attributable to common shareholders	5,436	2,729	4,302
Less: Dividends and undistributed earnings allocated to nonvested restricted shares	27	13	18
Net income from continuing operations attributable to basic common shareholders	5,409	2,716	4,284
Net income from discontinued operations attributable to common shareholders		4,555	827
Less: Undistributed earnings allocated to nonvested restricted shares		22	3
Net income from continuing operations attributable to diluted common shareholders	5,409	2,716	4,284
Net income from discontinued operations attributable to basic common shareholders		$ 4,533	$ 824
Basic weighted-average common shares outstanding (in shares)	426	427	447
Basic earnings (loss) per common share from continuing operations (in dollars per share)	$ 12.71	$ 6.37	$ 9.59
Basic earnings from discontinued operations (dollars per share)		10.62	1.84
Basic earnings per common share (dollars per share)	$ 12.71	$ 16.99	$ 11.43
Less: Impact of earnings per share dilution from discontinued operations		$ 2	$ 10
Net income from discontinued operations attributable to diluted common shareholders		$ 4,531	$ 814
Dilutive potential common shares			1
Diluted weighted-average common shares outstanding (in shares)	426	427	448
Diluted earnings (loss) per common share from continuing operations (in dollars per share)	$ 12.70	$ 6.36	$ 9.57
Diluted earnings from discontinued operations (dollars per share)		10.60	1.82
Diluted earnings per common share (dollars per share)	$ 12.70	$ 16.96	$ 11.39