LOANS - Consumer Troubled Debt Restructurings (Details) (Consumer, USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014 loan
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	55,702		66,948
Post-modification recorded investment	684		$ 1,082
Deferred principal	4		18
Contingent principal forgiveness	2		11
Principal forgiveness	9		12
Loans in default	168		346
In North America Offices | Residential first mortgages
Loans receivable
Number of loans modified	3,093		5,779
Post-modification recorded investment	407		685
Deferred principal	4		17
Contingent principal forgiveness	2		11
Principal forgiveness	8		3
Average interest rate reduction (as a percent)	1.00%		1.00%
Post-modification recorded investment for borrowers that have gone through Chapter 7 bankruptcy	66		91
Loans in default	110		245
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	38		57
In North America Offices | Home equity loans
Loans receivable
Number of loans modified	1,258		2,319
Post-modification recorded investment	46		84
Deferred principal	0		1
Contingent principal forgiveness	0		0
Principal forgiveness	1		9
Average interest rate reduction (as a percent)	2.00%		2.00%
Post-modification recorded investment for borrowers that have gone through Chapter 7 bankruptcy	15		22
Loans in default	11		23
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		19
In North America Offices | Credit cards
Loans receivable
Number of loans modified	50,310		44,976
Post-modification recorded investment	211		199
Deferred principal	0		0
Contingent principal forgiveness	0		0
Principal forgiveness	0		0
Average interest rate reduction (as a percent)	16.00%		15.00%
Loans in default	43		51
In North America Offices | Installment and other
Loans receivable
Number of loans modified	984		13,836
Post-modification recorded investment	9		101
Deferred principal	0		0
Contingent principal forgiveness	0		0
Principal forgiveness	0		0
Average interest rate reduction (as a percent)	12.00%		7.00%
Loans in default	2		21
In North America Offices | Commercial market loans
Loans receivable
Number of loans modified	57		38
Post-modification recorded investment	11		13
Deferred principal	0		0
Contingent principal forgiveness	0		0
Principal forgiveness	0		0
Average interest rate reduction (as a percent)	0.00%		0.00%
Loans in default	2		6
In offices outside North America
Loans receivable
Number of loans modified	57,344		52,642
Post-modification recorded investment	219		315
Deferred principal	0		0
Contingent principal forgiveness	0		0
Principal forgiveness	4		3
Loans in default	75		101
In offices outside North America | Residential first mortgages
Loans receivable
Number of loans modified	869		546
Post-modification recorded investment	21		22
Deferred principal	0		0
Contingent principal forgiveness	0		0
Principal forgiveness	0		0
Average interest rate reduction (as a percent)	0.00%		1.00%
Loans in default	6		6
In offices outside North America | Home equity loans
Loans receivable
Number of loans modified	14		32
Post-modification recorded investment	3		5
Deferred principal	0		0
Contingent principal forgiveness	0		0
Principal forgiveness	0		0
Average interest rate reduction (as a percent)	0.00%		0.00%
Loans in default	0		0
In offices outside North America | Credit cards
Loans receivable
Number of loans modified	40,431		37,106
Post-modification recorded investment	98		121
Deferred principal	0		0
Contingent principal forgiveness	0		0
Principal forgiveness	2		2
Average interest rate reduction (as a percent)	13.00%		14.00%
Loans in default	35		63
In offices outside North America | Installment and other
Loans receivable
Number of loans modified	15,947		14,862
Post-modification recorded investment	69		74
Deferred principal	0		0
Contingent principal forgiveness	0		0
Principal forgiveness	2		1
Average interest rate reduction (as a percent)	5.00%		7.00%
Loans in default	23		27
In offices outside North America | Commercial market loans
Loans receivable
Number of loans modified	83		96
Post-modification recorded investment	28		93
Deferred principal	0		0
Contingent principal forgiveness	0		0
Principal forgiveness	0		0
Average interest rate reduction (as a percent)	3.00%		0.00%
Loans in default	11		$ 5