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The cash inflow from securitizing loans held with the intention to resell in the near future.

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SECURITIES - Narrative (Details) - USD ($)	12 Months Ended
SECURITIES - Narrative (Details) - USD ($)	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Net securities impairment losses recognized in earnings	$ 12,000,000	$ 7,000,000	$ 10,000,000
Impaired debt securities sold	0	0	0
Pretax non-credit related losses were deferred in OCI	27,000,000	36,000,000	35,000,000
Taxable interest income from investment securities	584,000,000	621,000,000	619,000,000
Mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Securitizations of mortgage loans	68,000,000	3,000,000	18,000,000
Mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Value of held-to-maturity security sold		73,000,000
Gain recognized on sale of held-to-maturity security		2,000,000
Available-for-sale Securities
Schedule of Available-for-sale Securities [Line Items]
Cumulative credit losses recognized in earnings	75,000,000	66,000,000	62,000,000	$ 56,000,000
Credit impairments recognized in earnings on securities that have been previously impaired	12,000,000	7,000,000	10,000,000
Held-to-maturity Securities
Schedule of Available-for-sale Securities [Line Items]
Cumulative credit losses recognized in earnings	0	$ 0	$ 0
Proprietary Internal Model \| Available-for-sale Securities
Schedule of Available-for-sale Securities [Line Items]
Credit impairments recognized in earnings on securities that have been previously impaired	$ 5,000,000