FAIR VALUE MEASUREMENTS - Schedule of Financial Instruments not Recorded at Fair Value (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans and leases	$ 90,749	[1],[2]	$ 85,859	[1],[2]
Loans and leases	91,227		85,724
Other loans held for sale	3		1,078
Other loans held for sale	3		1,078
Securities held to maturity	5,289		4,315
Securities held-to-maturity	5,278		4,257
Other investment securities	893		935
Other investment securities	893		935
Deposits	93,463		86,903
Deposits	93,791		86,907
Deposits held for sale	0		5,277
Deposits held for sale			5,277
Federal funds purchased and securities sold under agreements to repurchase	5,184		4,791
Federal funds purchased and securities sold under agreements to repurchase	7,310		4,791
Other short-term borrowed funds	6,715		2,251
Other short-term borrowed funds	6,710		2,249
Long-term borrowed funds	2,062		1,405
Long-term borrowed funds	2,060		1,404
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans and leases	90,749		85,859
Other loans held for sale	3		1,078
Securities held to maturity	5,289		4,315
Other investment securities	893		935
Deposits	93,463		86,903
Deposits held for sale			5,277
Federal funds purchased and securities sold under agreements to repurchase	5,184		4,791
Other short-term borrowed funds	6,715		2,251
Long-term borrowed funds	2,062		1,405
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans and leases	0		0
Other loans held for sale	0		0
Securities held-to-maturity	0		0
Other investment securities	0		0
Deposits	0		0
Deposits held for sale			0
Federal funds purchased and securities sold under agreements to repurchase	0		0
Other short-term borrowed funds	0		0
Long-term borrowed funds	0		0
Level 1 | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans and leases	0		0
Other loans held for sale	0		0
Securities held to maturity	0		0
Other investment securities	0		0
Deposits	0		0
Deposits held for sale			0
Federal funds purchased and securities sold under agreements to repurchase	0		0
Other short-term borrowed funds	0		0
Long-term borrowed funds	0		0
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans and leases	103		74
Other loans held for sale	0		0
Securities held-to-maturity	5,278		4,257
Other investment securities	893		935
Deposits	93,791		86,907
Deposits held for sale			5,277
Federal funds purchased and securities sold under agreements to repurchase	7,310		4,791
Other short-term borrowed funds	6,710		2,249
Long-term borrowed funds	2,060		1,404
Level 2 | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans and leases	103		74
Other loans held for sale	0		0
Securities held to maturity	5,289		4,315
Other investment securities	893		935
Deposits	93,463		86,903
Deposits held for sale			5,277
Federal funds purchased and securities sold under agreements to repurchase	5,184		4,791
Other short-term borrowed funds	6,715		2,251
Long-term borrowed funds	2,062		1,405
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans and leases	91,124		85,650
Other loans held for sale	3		1,078
Securities held-to-maturity	0		0
Other investment securities	0		0
Deposits	0		0
Deposits held for sale			0
Federal funds purchased and securities sold under agreements to repurchase	0		0
Other short-term borrowed funds	0		0
Long-term borrowed funds	0		0
Level 3 | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans and leases	90,646		85,785
Other loans held for sale	3		1,078
Securities held to maturity	0		0
Other investment securities	0		0
Deposits	0		0
Deposits held for sale			0
Federal funds purchased and securities sold under agreements to repurchase	0		0
Other short-term borrowed funds	0		0
Long-term borrowed funds	$ 0		$ 0

[1] Excluded from the table above are loans held for sale totaling $208 million as of September 30, 2014 and $1.3 billion as of December 31, 2013. The December 31, 2013 loans held for sale balance primarily related to the Company's sale of certain assets and liabilities associated with its Chicago-area retail branches. For further discussion, see Note 13 "Divestitures and Branch Assets and Liabilities Held for Sale" to the Company's unaudited interim Consolidated Financial Statements included in Part I, Item 1 — Financial Information.

[2] Mortgage loans serviced for others by the Company's subsidiaries are not included above, and amounted to $18.1 billion and $18.7 billion at September 30, 2014 and December 31, 2013, respectively.