CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Millions	Total	Cumulative Effect, Period of Adoption, Adjustment	Preferred Stock	Common Stock	Additional Paid-in Capital	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Treasury Stock, at Cost	Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2021			2,000,000	422,000,000
Beginning balance at Dec. 31, 2021	$ 23,420		$ 2,014	$ 6	$ 19,005	$ 7,978		$ (4,918)	$ (665)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends to common stockholders	(360)					(360)
Dividends to preferred stockholders	(56)					(56)
Issuance of common stock - business acquisition (in shares)				72,000,000
Issuance of common stock - business acquisition	3,036				3,036
Treasury stock purchased	(2)							(2)
Share-based compensation plans (in shares)				2,000,000
Share-based compensation plans	46				46
Employee stock purchase plan	13				13
Total comprehensive income (loss):
Net income	784					784
Other comprehensive income (loss)	(2,553)								(2,553)
Total comprehensive income (loss)	(1,769)					784			(2,553)
Ending balance (in shares) at Jun. 30, 2022			2,000,000	496,000,000
Ending balance at Jun. 30, 2022	24,328		$ 2,014	$ 6	22,100	8,346		(4,920)	(3,218)
Beginning balance (in shares) at Mar. 31, 2022			2,000,000	423,000,000
Beginning balance at Mar. 31, 2022	22,074		$ 2,014	$ 6	19,021	8,209		(4,918)	(2,258)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends to common stockholders	(195)					(195)
Dividends to preferred stockholders	(32)					(32)
Issuance of common stock - business acquisition (in shares)				72,000,000
Issuance of common stock - business acquisition	3,036				3,036
Treasury stock purchased	(2)							(2)
Share-based compensation plans (in shares)				1,000,000
Share-based compensation plans	36				36
Employee stock purchase plan	7				7
Total comprehensive income (loss):
Net income	364					364
Other comprehensive income (loss)	(960)								(960)
Total comprehensive income (loss)	(596)					364			(960)
Ending balance (in shares) at Jun. 30, 2022			2,000,000	496,000,000
Ending balance at Jun. 30, 2022	24,328		$ 2,014	$ 6	22,100	8,346		(4,920)	(3,218)
Beginning balance (in shares) at Dec. 31, 2022			2,000,000	492,000,000
Beginning balance at Dec. 31, 2022	23,690	$ (26)	$ 2,014	$ 6	22,142	9,159	$ (26)	(5,071)	(4,560)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends to common stockholders	(410)					(410)
Dividends to preferred stockholders	$ (57)					(57)
Treasury stock purchased (in shares)	(19,736,783)			(20,000,000)
Treasury stock purchased	$ (656)							(656)
Share repurchase excise tax	(7)							(7)
Share-based compensation plans (in shares)				3,000,000
Share-based compensation plans	51				51
Employee stock purchase plan	14				14
Total comprehensive income (loss):
Net income	989					989
Other comprehensive income (loss)	(3)								(3)
Total comprehensive income (loss)	986					989			(3)
Ending balance (in shares) at Jun. 30, 2023			2,000,000	475,000,000
Ending balance at Jun. 30, 2023	23,585		$ 2,014	$ 6	22,207	9,655		(5,734)	(4,563)
Beginning balance (in shares) at Mar. 31, 2023			2,000,000	484,000,000
Beginning balance at Mar. 31, 2023	24,201		$ 2,014	$ 6	22,183	9,416		(5,475)	(3,943)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends to common stockholders	(205)					(205)
Dividends to preferred stockholders	(34)					(34)
Treasury stock purchased (in shares)				(10,000,000)
Treasury stock purchased	(256)							(256)
Share repurchase excise tax	(3)							(3)
Share-based compensation plans (in shares)				1,000,000
Share-based compensation plans	18				18
Employee stock purchase plan (in shares)				0
Employee stock purchase plan	6				6
Total comprehensive income (loss):
Net income	478					478
Other comprehensive income (loss)	(620)								(620)
Total comprehensive income (loss)	(142)					478			(620)
Ending balance (in shares) at Jun. 30, 2023			2,000,000	475,000,000
Ending balance at Jun. 30, 2023	$ 23,585		$ 2,014	$ 6	$ 22,207	$ 9,655		$ (5,734)	$ (4,563)