INTEREST REVENUE AND EXPENSE (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest revenue
Loan interest, including fees		$ 41,361	$ 39,752	$ 40,510
Deposits with banks		1,635	971	727
Federal funds sold and securities borrowed or purchased under agreements to resell		3,248	2,543	2,516
Investments, including dividends		8,295	7,582	7,017
Trading account assets		5,502	5,738	5,942
Other interest		1,163	1,029	1,839
Total interest revenue	[1]	61,204	57,615	58,551
Interest expense
Deposits		6,586	5,300	5,052
Federal funds purchased and securities loaned or sold under agreements to repurchase		2,661	1,912	1,612
Trading account liabilities		638	410	217
Short-term borrowings		1,059	477	523
Long-term debt		5,573	4,412	4,517
Total interest expense	[1]	16,517	12,511	11,921
Net interest revenue	[1]	44,687	45,104	46,630
Provision for loan losses		7,503	6,749	7,108
Net interest revenue after provision for loan losses		37,184	38,355	39,522
Insurance fees and charges		$ 1,249	$ 1,145	$ 1,118

[1] Certain prior-period revenue and expense lines and totals were reclassified to conform to the current period’s presentation. See Note 3 to the Consolidated Financial Statements.