MORTGAGE BANKING - Residential Mortgage Loan Sales (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Residential mortgages
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Residential mortgage loans sold with servicing retained	$ 5,272	$ 2,919
Mortgage banking fees
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Gain on sales	143	37
Contractually specified servicing, late and other anciliary fees	$ 58	$ 48

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- Definition

Amount of contractually specified servicing fee, late fee, and ancillary fee recognized as income for servicing asset and servicing liability.

+ References

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-Publisher FASB
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-SubTopic 50
-Section 50
-Paragraph 2
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- Definition

The gains (losses) included in earnings that represent the difference between the sale price and the carrying value of loans made to finance real estate acquisitions. This element refers to the gain (loss) and not to the cash proceeds of the sale. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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- Definition

The cash inflow from sales of loans that are secured with real estate mortgages and are held with the intention to resell in the near future.

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