Intangible Assets - Residential MSRs Activity (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Fair value of MSRs:
Beginning balance	$ 190	$ 228	$ 168	$ 220
Additions related to loan sales	5	6	11	14
Changes in fair value due to:
Change in valuation inputs or assumptions used in the valuation models	43	(31)	69	(15)
Realization of cash flows	(13)	(16)	(23)	(32)
Ending balance	$ 225	$ 187	$ 225	$ 187

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The value of new servicing assets, subsequently measured at fair value, acquired or created during the current period through purchases or from transfers of financial assets.

+ 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)(2)

-URI http://asc.fasb.org/extlink&oid=7882072&loc=d3e122625-111746

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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=7882072&loc=d3e122625-111746

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- Definition

The net increase or decrease in fair value as a result of changes in the inputs used to calculate the fair value of servicing assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 50

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=7882072&loc=d3e122625-111746

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- Definition

The net Increase or Decrease in fair value as a result of other changes that are not additions, disposals, or a result of change in the inputs, assumptions, or model used to calculate the fair value of servicing assets.

+ 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)(4)(ii)

-URI http://asc.fasb.org/extlink&oid=7882072&loc=d3e122625-111746

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