Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Millions	Total	Preferred stock	Common stock	Additional paid-in capital	Retained earnings	Accumulated other comprehensive income/(loss)	Shares held in RSU Trust, at cost	Treasury stock, at cost
Beginning balance at Dec. 31, 2017		$ 26,068	$ 4,105	$ 90,579	$ 177,676	$ (119)	$ (21)	$ (42,595)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance		1,696
Redemption		0
Shares issued and commitments to issue common stock for employee shared-based compensation awards, and related tax effects				(897)
Other				(349)
Net income	$ 25,408				25,408
Dividends declared:
Preferred stock					(1,167)
Common stock					(6,554)
Other comprehensive income/(loss), after-tax	(2,394)					(2,394)
Repurchase								(14,055)
Reissuance								1,670
Ending balance at Sep. 30, 2018	258,956	27,764	4,105	89,333	195,180	(2,425)	(21)	(54,980)
Beginning balance at Jun. 30, 2018		26,068	4,105	89,392	189,881	(1,138)	(21)	(50,829)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance		1,696
Redemption		0
Shares issued and commitments to issue common stock for employee shared-based compensation awards, and related tax effects				179
Other				(238)
Net income	8,380				8,380
Dividends declared:
Preferred stock					(379)
Common stock					(2,702)
Other comprehensive income/(loss), after-tax	(1,287)					(1,287)
Repurchase								(4,416)
Reissuance								265
Ending balance at Sep. 30, 2018	258,956	27,764	4,105	89,333	195,180	(2,425)	(21)	(54,980)
Beginning balance at Dec. 31, 2018	256,515	26,068	4,105	89,162	199,202	(1,507)	(21)	(60,494)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance		4,100
Redemption		(1,805)
Shares issued and commitments to issue common stock for employee shared-based compensation awards, and related tax effects				(604)
Other				(46)
Net income	27,911				27,911
Dividends declared:
Preferred stock					(1,201)
Common stock					(8,086)
Other comprehensive income/(loss), after-tax	3,307					3,307
Repurchase								(17,250)
Reissuance								1,445
Ending balance at Sep. 30, 2019	264,348	28,363	4,105	88,512	217,888	1,800	(21)	(76,299)
Beginning balance at Jun. 30, 2019		26,993	4,105	88,359	212,093	1,114	(21)	(69,428)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance		2,250
Redemption		(880)
Shares issued and commitments to issue common stock for employee shared-based compensation awards, and related tax effects				156
Other				(3)
Net income	9,080				9,080
Dividends declared:
Preferred stock					(423)
Common stock					(2,862)
Other comprehensive income/(loss), after-tax	686					686
Repurchase								(6,949)
Reissuance								78
Ending balance at Sep. 30, 2019	$ 264,348	$ 28,363	$ 4,105	$ 88,512	$ 217,888	$ 1,800	$ (21)	$ (76,299)