Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Nonvoting Common Stock	Preferred Stock	Common Stock	Common Stock Common Stock	Common Stock Nonvoting Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock, at cost	Accumulated Other Comprehensive Income (Loss)
Balance at beginning of period at Dec. 31, 2022	$ 36,608.0			$ 9,706.0		$ 20.0	$ 1.0	$ 27,075.0	$ 31,066.0	$ (8,639.0)	$ (22,621.0)
Beginning balance (in shares) at Dec. 31, 2022						2,023	51
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,603.0	$ 1,559.0	$ 44.0						1,603.0
Other comprehensive income (loss), net of tax	1,931.0										1,931.0
Redemption and repurchase of preferred stock, inclusive of tax	(471.0)			(515.0)					44.0
Dividends declared on preferred stock	(105.4)								(105.0)
Dividends declared on common stock — $.25 per share	(464.0)								(464.0)
Repurchase of common stock, inclusive of tax	(2,869.0)				$ (2,800.0)					(2,869.0)
Stock option exercises and other	19.0							(92.0)		111.0
Share-based compensation	129.0							129.0
Other	(34.0)							24.0		(58.0)
Balance at end of period at Mar. 31, 2023	36,347.0			9,191.0		$ 20.0	$ 1.0	27,136.0	32,144.0	(11,455.0)	(20,690.0)
Ending balance (in shares) at Mar. 31, 2023						2,023	51
Balance at beginning of period at Dec. 31, 2023	40,958.0			9,191.0		$ 20.0	$ 1.0	27,330.0	33,901.0	(11,354.0)	(18,131.0)
Beginning balance (in shares) at Dec. 31, 2023						2,023	51
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,362.0	$ 1,324.0	$ 38.0						1,362.0
Other comprehensive income (loss), net of tax	555.0										555.0
Dividends declared on preferred stock	(103.1)								(103.0)
Dividends declared on common stock — $.25 per share	(459.0)								(459.0)
Stock option exercises and other	22.0							(120.0)		142.0
Share-based compensation	125.0							125.0
Other	(48.0)							23.0		(71.0)
Balance at end of period at Mar. 31, 2024	$ 42,412.0			$ 9,191.0		$ 20.0	$ 1.0	$ 27,358.0	$ 34,701.0	$ (11,283.0)	$ (17,576.0)
Ending balance (in shares) at Mar. 31, 2024						2,023	51