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, 2016		$ 26,068	$ 4,105	$ 91,627	$ 162,440	$ (1,175)	$ (21)	$ (28,854)
Cumulative effect of changes in accounting principles at Dec. 31, 2016					0	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance		0
Shares issued and commitments to issue common stock for employee shared-based compensation awards, and related tax effects				(680)
Other				(250)
Net income	$ 20,209				20,209
Dividends declared:
Preferred stock					(1,235)
Common stock ($1.92 and $1.56 per share)					(5,587)
Other comprehensive income/(loss)	866					866
Repurchase								(10,602)
Reissuance								1,471
Ending balance at Sep. 30, 2017	258,382	26,068	4,105	90,697	175,827	(309)	(21)	(37,985)
Beginning balance at Jun. 30, 2017						(392)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	6,732
Dividends declared:
Other comprehensive income/(loss)	83
Ending balance at Sep. 30, 2017	258,382	26,068	4,105	90,697	175,827	(309)	(21)	(37,985)
Beginning balance at Dec. 31, 2017	255,693	26,068	4,105	90,579	177,676	(119)	(21)	(42,595)
Cumulative effect of changes in accounting principles at Dec. 31, 2017					(183)	88
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance		1,696
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 ($1.92 and $1.56 per share)					(6,554)
Other comprehensive income/(loss)	(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						(1,138)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	8,380
Dividends declared:
Other comprehensive income/(loss)	(1,287)
Ending balance at Sep. 30, 2018	$ 258,956	$ 27,764	$ 4,105	$ 89,333	$ 195,180	$ (2,425)	$ (21)	$ (54,980)