Debt - Key Components of Long-term Debt (Details) (USD $)	3 Months Ended
Mar. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Carrying Value	$ 5,495,000,000us-gaap_LongTermDebt	$ 5,495,000,000us-gaap_LongTermDebt
Long-term Notes $2.5B
Debt Instrument [Line Items]
Debt, face amount	2,500,000,000
Stated interest rate	1.875%
Issued at Discount to Par	99.943%
Carrying Value	2,499,000,000
Long-term Notes $2.0B
Debt Instrument [Line Items]
Debt, face amount	2,000,000,000
Stated interest rate	2.65%
Issued at Discount to Par	99.76%
Carrying Value	1,996,000,000
Long-term Notes $1.0B
Debt Instrument [Line Items]
Debt, face amount	1,000,000,000
Stated interest rate	3.375%
Issued at Discount to Par	99.925%
Carrying Value	1,000,000,000
Long-term Notes $5.5B
Debt Instrument [Line Items]
Carrying Value	$ 5,495,000,000

Face (par) amount of debt instrument at time of issuance.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

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- Definition

Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

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- Definition

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

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

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

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