ALLOWANCE FOR CREDIT LOSSES, NONPERFORMING ASSETS, AND CONCENTRATIONS OF CREDIT RISK - Accruing and Nonaccruing Past Due Amounts (Details) - USD ($) $ in Millions		Jun. 30, 2015	Dec. 31, 2014
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due		$ 473	$ 510
90 Days or More Past Due		807	872
Total Past Due		1,280	1,382
Commercial Banking
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due		85	86
90 Days or More Past Due		125	164
Total Past Due		210	250
Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due		58	57
90 Days or More Past Due		83	114
Total Past Due		141	171
Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due		25	26
90 Days or More Past Due		42	50
Total Past Due		67	76
Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due		2	3
90 Days or More Past Due		0	0
Total Past Due		2	3
Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due		388	424
90 Days or More Past Due		682	708
Total Past Due		1,070	1,132
Residential mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due		65	97
90 Days or More Past Due		246	269
Total Past Due		311	366
Home equity loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due		48	60
90 Days or More Past Due		135	145
Total Past Due		183	205
Home equity lines of credit
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due		73	73
90 Days or More Past Due		185	198
Total Past Due		258	271
Home equity loans serviced by others
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	[1]	20	26
90 Days or More Past Due	[1]	21	23
Total Past Due	[1]	41	49
Home equity lines of credit serviced by others
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	[1]	22	10
90 Days or More Past Due	[1]	21	19
Total Past Due	[1]	43	29
Automobile
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due		104	93
90 Days or More Past Due		22	16
Total Past Due		126	109
Student
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due		24	25
90 Days or More Past Due		35	17
Total Past Due		59	42
Credit cards
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due		18	22
90 Days or More Past Due		14	17
Total Past Due		32	39
Other retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due		14	18
90 Days or More Past Due		3	4
Total Past Due		$ 17	$ 22

[1] The Company’s SBO portfolio consists of purchased home equity loans and lines that were originally serviced by others. The Company now services a portion of this portfolio internally.