Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Millions	Total	Preferred stock	Common stock	Additional paid-in capital	Retained earnings	Retained earnings Cumulative effect of a change in accounting principle	Accumulated other comprehensive income/(loss)	Shares held in RSU Trust, at cost	Treasury stock, at cost
Beginning balance at Dec. 31, 2019		$ 26,993	$ 4,105	$ 88,522	$ 223,211	$ (2,650)	$ 1,569	$ (21)	$ (83,049)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance		4,500
Redemption		(1,430)
Shares issued and commitments to issue common stock for employee share-based compensation awards, and related tax effects				(392)
Other				(5)
Net income	$ 7,552				7,552
Dividends declared:
Preferred stock					(822)
Common stock ($0.90 and $0.90 per share and $1.80 and $1.80 per share, respectively)					(5,559)
Other comprehensive income/(loss), after-tax	7,220						7,220
Liquidation of RSU Trust								10
Repurchase									(6,397)
Reissuance									1,109
Ending balance at Jun. 30, 2020	264,466	30,063	4,105	88,125	221,732		8,789	(11)	(88,337)
Beginning balance at Mar. 31, 2020		30,063	4,105	87,857	220,226		7,418	(21)	(88,386)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance		0
Redemption		0
Shares issued and commitments to issue common stock for employee share-based compensation awards, and related tax effects				268
Other				0
Net income	4,687				4,687
Dividends declared:
Preferred stock					(401)
Common stock ($0.90 and $0.90 per share and $1.80 and $1.80 per share, respectively)					(2,780)
Other comprehensive income/(loss), after-tax	1,371						1,371
Liquidation of RSU Trust								10
Repurchase									0
Reissuance									49
Ending balance at Jun. 30, 2020	264,466	30,063	4,105	88,125	221,732		8,789	(11)	(88,337)
Beginning balance at Dec. 31, 2020	279,354	30,063	4,105	88,394	236,990		7,986	0	(88,184)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance		5,350
Redemption		(2,575)
Shares issued and commitments to issue common stock for employee share-based compensation awards, and related tax effects				(134)
Other				(66)
Net income	26,248				26,248
Dividends declared:
Preferred stock					(772)
Common stock ($0.90 and $0.90 per share and $1.80 and $1.80 per share, respectively)					(5,483)
Other comprehensive income/(loss), after-tax	(5,416)						(5,416)
Liquidation of RSU Trust								0
Repurchase									(11,200)
Reissuance									1,080
Ending balance at Jun. 30, 2021	286,386	32,838	4,105	88,194	256,983		2,570	0	(98,304)
Beginning balance at Mar. 31, 2021		31,563	4,105	88,005	248,151		1,041	0	(92,151)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance		3,850
Redemption		(2,575)
Shares issued and commitments to issue common stock for employee share-based compensation awards, and related tax effects				229
Other				(40)
Net income	11,948				11,948
Dividends declared:
Preferred stock					(393)
Common stock ($0.90 and $0.90 per share and $1.80 and $1.80 per share, respectively)					(2,723)
Other comprehensive income/(loss), after-tax	1,529						1,529
Liquidation of RSU Trust								0
Repurchase									(6,201)
Reissuance									48
Ending balance at Jun. 30, 2021	$ 286,386	$ 32,838	$ 4,105	$ 88,194	$ 256,983		$ 2,570	$ 0	$ (98,304)