CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (unaudited) - USD ($) $ in Millions	Total	Series I Preferred Stock	Series J Preferred Stock	Series K Preferred Stock	Series L Preferred Stock	Class B, Series A Preferred Stock	Common Stock	Preferred Stock	Capital Surplus	Retained Earnings	Retained Earnings Series I Preferred Stock	Retained Earnings Series J Preferred Stock	Retained Earnings Series K Preferred Stock	Retained Earnings Series L Preferred Stock	Retained Earnings Class B, Series A Preferred Stock	Accumulated Other Comprehensive (Loss) Income	Treasury Stock
Beginning Balance at Dec. 31, 2020	$ 23,111						$ 2,051	$ 2,116	$ 3,635	$ 18,384						$ 2,601	$ (5,676)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	694									694
Other comprehensive income (loss), net of tax	(809)															(809)
Cash dividends declared:
Common stock	(195)									(195)
Preferred stock		$ (7)	$ (3)	$ (3)	$ (4)	$ (3)					$ (7)	$ (3)	$ (3)	$ (4)	$ (3)
Shares acquired for treasury	(180)																(180)
Impact of stock transactions under stock compensation plans, net	(6)								(43)								37
Ending Balance at Mar. 31, 2021	22,595						2,051	2,116	3,592	18,863						1,792	(5,819)
Beginning Balance at Dec. 31, 2021	22,210						2,051	2,116	3,624	20,236						1,207	(7,024)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	494									494
Other comprehensive income (loss), net of tax	(2,303)															(2,303)
Cash dividends declared:
Common stock	(209)									(209)
Preferred stock		$ (7)	$ (3)	$ (3)	$ (4)	$ (3)					$ (7)	$ (3)	$ (3)	$ (4)	$ (3)
Impact of stock transactions under stock compensation plans, net	5								(9)								14
Ending Balance at Mar. 31, 2022	$ 20,177						$ 2,051	$ 2,116	$ 3,615	$ 20,501						$ (1,096)	$ (7,010)