LOANS - Consumer Loans (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($) category	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) category	Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Loans
Number of loan categories | category	2		2
Loans, net of unearned income	$ 632,118		$ 632,118		$ 644,635
Consumer
Loans
Total loans	343,030		343,030		370,652
Net unearned income	(681)		(681)		(682)
Loans, net of unearned income	342,349		342,349		369,970
Loans sold and/or reclassified to held-for-sale	1,500	$ 3,400	14,600	$ 3,800
Consumer | In U.S. offices
Loans
Total loans	209,260		209,260		229,860
Consumer | In U.S. offices | Mortgage and real estate
Loans
Total loans	90,715		90,715		96,533
Consumer | In U.S. offices | Installment, revolving credit and other
Loans
Total loans	4,956		4,956		14,450
Consumer | In U.S. offices | Cards
Loans
Total loans	107,096		107,096		112,982
Consumer | In U.S. offices | Commercial and industrial
Loans
Total loans	6,493		6,493		5,895
Consumer | In offices outside the U.S.
Loans
Total loans	133,770		133,770		140,792
Consumer | In offices outside the U.S. | Mortgage and real estate
Loans
Total loans	50,704		50,704		54,462
Consumer | In offices outside the U.S. | Installment, revolving credit and other
Loans
Total loans	30,958		30,958		31,128
Consumer | In offices outside the U.S. | Cards
Loans
Total loans	28,662		28,662		32,032
Consumer | In offices outside the U.S. | Commercial and industrial
Loans
Total loans	22,953		22,953		22,561
Consumer | In offices outside the U.S. | Lease financing
Loans
Total loans	$ 493		$ 493		$ 609