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Amount of operating interest income, including amortization and accretion of premiums and discounts, on securities subject to state, federal and other income tax.

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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 ($) $ in Millions	12 Months Ended
SECURITIES - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Taxable interest income from investment securities	$ 625	$ 584	$ 621
Impaired debt securities sold	0	0	0
Pretax non-credit related losses were deferred in OCI	0	27	36
Available-for-sale Securities
Schedule of Available-for-sale Securities [Line Items]
Cumulative credit losses recognized in earnings	80	75	66	$ 62
Credit impairments recognized in earnings on securities that have been previously impaired	7	12	7
Available-for-sale Securities \| Proprietary Internal Model
Schedule of Available-for-sale Securities [Line Items]
Credit impairments recognized in earnings on securities that have been previously impaired		5
Held-to-maturity Securities
Schedule of Available-for-sale Securities [Line Items]
Cumulative credit losses recognized in earnings	0	0	0
Mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Securitizations of mortgage loans	$ 134	$ 68	3
Mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Value of held-to-maturity security sold			73
Gain on other than temporary impairments			$ 2