LOANS - Consumer Troubled Debt Restructurings (Details) - Consumer $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015 USD ($) loan	Jun. 30, 2014 USD ($) loan	Jun. 30, 2015 USD ($) loan	Jun. 30, 2014 USD ($) loan	Dec. 31, 2014
Loans receivable
Period within which default occurred post-modification			1 year
Number of days past due, non-accrual status			60 days
Residential first mortgages
Loans receivable
Number of days past due, non-accrual status			90 days		90 days
Home equity loans
Loans receivable
Number of days past due, non-accrual status			90 days
Credit cards
Loans receivable
Number of days past due, non-accrual status			180 days
Installment and other
Loans receivable
Number of days past due, non-accrual status			90 days
Commercial market loans
Loans receivable
Number of days past due, non-accrual status			90 days
In North America Offices
Loans receivable
Number of loans modified | loan	50,040	60,239	105,742	127,187
Post-modification recorded investment	$ 621	$ 904	$ 1,305	$ 1,987
Deferred principal	2	11	7	30
Contingent principal forgiveness	1	7	3	19
Principal forgiveness	9	4	19	17
Loans in default	$ 179	$ 255	$ 346	$ 600
In North America Offices | Residential first mortgages
Loans receivable
Number of loans modified | loan	2,709	4,723	5,802	10,502
Post-modification recorded investment	$ 366	$ 555	$ 773	$ 1,240
Deferred principal	2	10	6	28
Contingent principal forgiveness	1	7	3	19
Principal forgiveness	$ 8	$ 2	$ 17	$ 6
Average interest rate reduction (as a percent)	1.00%	1.00%	1.00%	1.00%
Post-modification recorded investment for borrowers that have gone through Chapter 7 bankruptcy	$ 62	$ 75	$ 127	$ 166
Loans in default	117	168	227	413
In North America Offices | Residential first mortgages | New OCC guidance
Loans receivable
Post-modification recorded investment for borrowers that have gone through Chapter 7 bankruptcy	$ 35	$ 42	$ 73	$ 99
In North America Offices | Home equity loans
Loans receivable
Number of loans modified | loan	1,292	1,883	2,550	4,202
Post-modification recorded investment	$ 45	$ 69	$ 90	$ 153
Deferred principal	0	1	1	2
Contingent principal forgiveness	0	0	0	0
Principal forgiveness	$ 1	$ 2	$ 2	$ 11
Average interest rate reduction (as a percent)	2.00%	3.00%	2.00%	2.00%
Post-modification recorded investment for borrowers that have gone through Chapter 7 bankruptcy	$ 15	$ 21	$ 29	$ 43
Loans in default	10	17	21	40
In North America Offices | Home equity loans | New OCC guidance
Loans receivable
Post-modification recorded investment for borrowers that have gone through Chapter 7 bankruptcy	$ 12	$ 18	$ 24	$ 37
In North America Offices | Credit cards
Loans receivable
Number of loans modified | loan	44,848	42,750	95,158	87,726
Post-modification recorded investment	$ 184	$ 190	$ 396	$ 390
Deferred principal	0	0	0	0
Contingent principal forgiveness	0	0	0	0
Principal forgiveness	$ 0	$ 0	$ 0	$ 0
Average interest rate reduction (as a percent)	16.00%	15.00%	16.00%	15.00%
Loans in default	$ 49	$ 48	$ 92	$ 99
In North America Offices | Installment and other
Loans receivable
Number of loans modified | loan	1,092	10,830	2,076	24,666
Post-modification recorded investment	$ 9	$ 81	$ 18	$ 182
Deferred principal	0	0	0	0
Contingent principal forgiveness	0	0	0	0
Principal forgiveness	$ 0	$ 0	$ 0	$ 0
Average interest rate reduction (as a percent)	14.00%	6.00%	13.00%	6.00%
Loans in default	$ 2	$ 21	$ 3	$ 41
In North America Offices | Commercial market loans
Loans receivable
Number of loans modified | loan	99	53	156	91
Post-modification recorded investment	$ 17	$ 9	$ 28	$ 22
Deferred principal	0	0	0	0
Contingent principal forgiveness	0	0	0	0
Principal forgiveness	$ 0	$ 0	$ 0	$ 0
Average interest rate reduction (as a percent)	0.00%	0.00%	0.00%	0.00%
Loans in default	$ 1	$ 1	$ 3	$ 7
In offices outside the U.S.
Loans receivable
Number of loans modified | loan	51,565	46,858	108,909	99,500
Post-modification recorded investment	$ 212	$ 253	$ 432	$ 569
Deferred principal	0	0	0	0
Contingent principal forgiveness	0	0	0	0
Principal forgiveness	4	4	8	8
Loans in default	$ 72	$ 187	$ 146	$ 289
In offices outside the U.S. | Residential first mortgages
Loans receivable
Number of loans modified | loan	742	746	1,611	1,292
Post-modification recorded investment	$ 23	$ 27	$ 44	$ 49
Deferred principal	0	0	0	0
Contingent principal forgiveness	0	0	0	0
Principal forgiveness	$ 0	$ 0	$ 0	$ 1
Average interest rate reduction (as a percent)	0.00%	1.00%	0.00%	1.00%
Loans in default	$ 6	$ 5	$ 12	$ 11
In offices outside the U.S. | Home equity loans
Loans receivable
Number of loans modified | loan	16	6	30	38
Post-modification recorded investment	$ 2	$ 1	$ 5	$ 6
Deferred principal	0	0	0	0
Contingent principal forgiveness	0	0	0	0
Principal forgiveness	$ 0	$ 0	$ 0	$ 0
Average interest rate reduction (as a percent)	0.00%	0.00%	0.00%	0.00%
Loans in default	$ 0	$ 0	$ 0	$ 0
In offices outside the U.S. | Credit cards
Loans receivable
Number of loans modified | loan	37,587	31,763	78,018	68,869
Post-modification recorded investment	$ 103	$ 112	$ 201	$ 234
Deferred principal	0	0	0	0
Contingent principal forgiveness	0	0	0	0
Principal forgiveness	$ 2	$ 2	$ 4	$ 4
Average interest rate reduction (as a percent)	12.00%	14.00%	13.00%	14.00%
Loans in default	$ 36	$ 59	$ 71	$ 122
In offices outside the U.S. | Installment and other
Loans receivable
Number of loans modified | loan	13,167	14,219	29,114	29,081
Post-modification recorded investment	$ 61	$ 72	$ 131	$ 146
Deferred principal	0	0	0	0
Contingent principal forgiveness	0	0	0	0
Principal forgiveness	$ 2	$ 2	$ 4	$ 3
Average interest rate reduction (as a percent)	6.00%	13.00%	5.00%	10.00%
Loans in default	$ 23	$ 28	$ 46	$ 56
In offices outside the U.S. | Commercial market loans
Loans receivable
Number of loans modified | loan	53	124	136	220
Post-modification recorded investment	$ 23	$ 41	$ 51	$ 134
Deferred principal	0	0	0	0
Contingent principal forgiveness	0	0	0	0
Principal forgiveness	$ 0	$ 0	$ 0	$ 0
Average interest rate reduction (as a percent)	1.00%	1.00%	2.00%	1.00%
Loans in default	$ 7	$ 95	$ 17	$ 100