Acquired Property Net (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Acquired Property [Roll Forward]
Acquired Property, Beginning Balance	$ 12,307us-gaap_RealEstateGrossAtCarryingValue	$ 11,158us-gaap_RealEstateGrossAtCarryingValue	$ 12,401us-gaap_RealEstateGrossAtCarryingValue
Acquired Property, Additions	13,100	16,092	16,915
Acquired Property, Disposals	(13,965)us-gaap_RealEstateCostOfRealEstateSold	(14,943)us-gaap_RealEstateCostOfRealEstateSold	(18,158)us-gaap_RealEstateCostOfRealEstateSold
Acquired Property, Ending Balance	11,442us-gaap_RealEstateGrossAtCarryingValue	12,307us-gaap_RealEstateGrossAtCarryingValue	11,158us-gaap_RealEstateGrossAtCarryingValue
Real Estate Owned Valuation Allowance [Roll Forward]
Valuation Allowance, Beginning Balance	(686)	(669)	(1,028)
Valuation Allowance, Period (Increase) Decrease	(138)	(17)	359
Valuation Allowance, Ending Balance	(824)	(686)	(669)
Acquired property, net	$ 10,618	$ 11,621	$ 10,489

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Carrying amount as of the balance sheet date of land and buildings obtained through foreclosure proceedings or defeasance in full or partial satisfaction of a debt arrangement.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 45

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4437-111522

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 28

-Article 12

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph c

-Subparagraph Schedule III

-Article 5

+ Details

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- Definition

Amount of real estate investments acquired through foreclosure for entities with a substantial portion of business acquiring and holding investment real estate.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 10

-Section S99

-Paragraph 6

-Subparagraph (SX 210.5-04.(c) Schedule III)

-URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 28

-Article 12

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph c

-Subparagraph Schedule III

-Article 5

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 970

-SubTopic 360

-Section S99

-Paragraph 1

-Subparagraph (SX 210.12-28.4)

-URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024

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- Definition

Amount of real estate investments sold for entities with a substantial portion of business acquiring and holding investment real estate.

+ References

+ Details

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- Definition

Amount, before accumulated depreciation, of real estate investments for entities with a substantial portion of business acquiring and holding investment real estate.

+ References

+ Details

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- Definition

For each period for which an income statement is required, disclosure of the changes in the allowance, including balances at end of period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.10(4))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 10

-Subparagraph 4

-Article 9

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- Definition

Total Increase or Decrease in the real estate owned valuation allowance for period.

+ References

+ Details

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