Fair Value Measurements - Instruments measured at fair value on a recurring basis (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Fair Value Measurements
Mortgage servicing rights	$ 483	$ 476
Assets related to discontinued operations	4	214
Mortgage servicing rights secured liability	437	419
Recurring basis \| Level One
Fair Value Measurements
Mortgage loans held for sale	0	0
Mortgage servicing rights	0	0
Assets related to discontinued operations	0	0
Mortgage servicing rights secured liability	0	0
Liability to deliver MSRs	0	0
Recurring basis \| Level One \| Interest rate lock commitments
Fair Value Measurements
Interest rate lock commitments	0	0
Recurring basis \| Level Two
Fair Value Measurements
Mortgage loans held for sale	50	94
Mortgage servicing rights	0	0
Assets related to discontinued operations	3	167
Mortgage servicing rights secured liability	0	0
Liability to deliver MSRs	0	0
Recurring basis \| Level Two \| Interest rate lock commitments
Fair Value Measurements
Interest rate lock commitments	0	0
Recurring basis \| Level Three
Fair Value Measurements
Mortgage loans held for sale	5	9
Mortgage servicing rights	483	476
Assets related to discontinued operations	0	1
Mortgage servicing rights secured liability	437	419
Liability to deliver MSRs	1	2
Recurring basis \| Level Three \| Interest rate lock commitments
Fair Value Measurements
Interest rate lock commitments	2	4
Recurring basis \| Total
Fair Value Measurements
Mortgage loans held for sale	55	103
Mortgage servicing rights	483	476
Assets related to discontinued operations	3	168
Mortgage servicing rights secured liability	437	419
Liability to deliver MSRs	1	2
Recurring basis \| Total \| Interest rate lock commitments
Fair Value Measurements
Interest rate lock commitments	$ 2	$ 4

Liability To Deliver Mortgage Servicing Rights

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- Definition

Mortgage Servicing Rights Secured Borrowing Liability

+ References

No definition available.

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- Definition

Amount classified as assets attributable to disposal group held for sale or disposed of.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=84176398&loc=d3e2941-110230

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 45
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=65878427&loc=d3e1107-107759

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5B
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-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721673-107760

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=65878427&loc=SL51721533-107759

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Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and elected not to be offset.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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- Definition

Fair value portion of mortgage loans held-for-sale.

+ References

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- Definition

Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=68078379&loc=d3e122625-111746

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