MORTGAGE BANKING - Changes Related to MSRs - Amortization Method (Details) - Residential mortgages - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
MSRs:
Balance as of beginning of period	$ 217	$ 170	$ 201	$ 167
Amount capitalized	11	9	26	28
Purchases	0	0	16	0
Amortization	(9)	(8)	(24)	(24)
Carrying amount before valuation allowance	219	171	219	171
Valuation allowance for servicing assets:
Balance at beginning of period	0	4	3	5
Valuation recoveries	0	0	(3)	(1)
Balance at end of period	0	4	0	4
Net carrying value of MSRs	$ 219	$ 167	$ 219	$ 167

Servicing Asset at Amortized Cost, Amount Capitalized

No definition available.

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- Definition

Amortized amount after valuation allowance of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

+ References

No definition available.

+ Details

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- Definition

Amortized amount of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 50
-Paragraph 4
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=68078379&loc=d3e122739-111746

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 45
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-Publisher FASB
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-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=7524895&loc=d3e120260-111741

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6469459&loc=d3e122492-111745

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- Definition

Amount of additions from purchases, assumption or transfer to contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

+ References

+ Details

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- Definition

Amount of amortization of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

+ References

+ Details

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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- Definition

Reflects the estimated amount of impairment as of the balance sheet date of recognized servicing assets that are being amortized in proportion to and over the period of estimated net servicing income or loss.

+ References

+ Details

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- Definition

Amount of increase (decrease) in the valuation allowance for impairment of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer from expenses (recoveries) recognized.

+ References

+ Details

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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