BORROWED FUNDS - Short Term Borrowed Debt Key Data (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Federal funds purchased
Short-term Debt [Line Items]
Weighted-average interest rate at period end	0.12%	0.09%
Maximum amount outstanding at month-end during the period	$ 7,022	$ 5,114
Average amount outstanding during the period	5,908	2,400
Weighted-average interest rate during the period	0.08%	0.31%
Other short-term borrowed funds
Short-term Debt [Line Items]
Weighted-average interest rate at period end	0.25%	0.20%
Maximum amount outstanding at month-end during the period	7,702	2,251
Average amount outstanding during the period	$ 5,479	$ 259
Weighted-average interest rate during the period	0.26%	0.44%