Debt (Debt) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Long-term Debt	$ 11,619us-gaap_LongTermDebt	$ 11,122us-gaap_LongTermDebt
Debt and Capital Lease Obligations	11,717us-gaap_DebtAndCapitalLeaseObligations	11,282us-gaap_DebtAndCapitalLeaseObligations
Debt, Current	197	199
Long-term Debt, Excluding Current Maturities	11,520	11,083
Unsecured Debt [Member]
Debt Instrument [Line Items]
Long-term Debt	3,450	2,800
Loans Payable [Member]
Debt Instrument [Line Items]
Long-term Debt	2,792	2,799
Corporate Debt Securities [Member]
Debt Instrument [Line Items]
Long-term Debt	1,928	2,075
Notes Payable, Other Payables [Member]
Debt Instrument [Line Items]
Long-term Debt	1,762	1,810
Secured Debt [Member]
Debt Instrument [Line Items]
Long-term Debt	1,592	1,596
Capital Lease Obligations [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 193	$ 202

Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.16)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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

-Publisher FASB

-Name Accounting Standards Codification

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-Section S99

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Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 7

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

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-Name Accounting Standards Codification

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-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

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

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

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Reference 5: http://www.xbrl.org/2003/role/presentationRef

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Reference 6: http://www.xbrl.org/2003/role/presentationRef

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-Topic 944

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-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.16)

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- Definition

Amount of long-term debt and capital lease obligation due after one year or beyond the normal operating cycle, if longer.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 6

-Section H

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Amount of long-term debt and capital leases due within one year or the normal operating cycle, if longer.

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