LOANS - Corporate Loans (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Loans
Loans, net of unearned income	$ 632,118	$ 644,635
Corporate
Loans
Total loans	290,370	275,219
Net unearned income (loss)	(601)	(554)
Loans, net of unearned income	289,769	274,665
Corporate | Commercial and industrial
Loans
Loans, net of unearned income	119,022	110,389
Corporate | Financial institutions
Loans
Loans, net of unearned income	65,964	67,832
Corporate | Mortgage and real estate
Loans
Loans, net of unearned income	40,555	38,473
Corporate | Lease financing
Loans
Loans, net of unearned income	2,016	2,113
In U.S. offices | Corporate
Loans
Total loans	146,326	134,829
In U.S. offices | Corporate | Commercial and industrial
Loans
Total loans	40,697	35,055
In U.S. offices | Corporate | Financial institutions
Loans
Total loans	37,360	36,272
In U.S. offices | Corporate | Mortgage and real estate
Loans
Total loans	34,680	32,537
In U.S. offices | Corporate | Installment, revolving credit and other
Loans
Total loans	31,882	29,207
In U.S. offices | Corporate | Lease financing
Loans
Total loans	1,707	1,758
In offices outside the U.S. | Corporate
Loans
Total loans	144,044	140,390
In offices outside the U.S. | Corporate | Commercial and industrial
Loans
Total loans	83,184	79,239
In offices outside the U.S. | Corporate | Financial institutions
Loans
Total loans	29,675	33,269
In offices outside the U.S. | Corporate | Mortgage and real estate
Loans
Total loans	5,948	6,031
In offices outside the U.S. | Corporate | Installment, revolving credit and other
Loans
Total loans	20,214	19,259
In offices outside the U.S. | Corporate | Lease financing
Loans
Total loans	309	356
In offices outside the U.S. | Corporate | Government and official institutions
Loans
Total loans	$ 4,714	$ 2,236