Debt (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Total debt	$ 3,611	$ 795
Less: short-term debt including current maturities	143	0
Long-term debt	3,468	795
Commercial Paper [Member]
Debt Instrument [Line Items]
Short-term debt	143	0
Senior Notes [Member] \| 5.9% Senior Notes, due 2017 [Member]
Debt Instrument [Line Items]
Senior notes	399	399
Unamortized debt discount and issuance costs	1
Senior Notes [Member] \| 2.5% Senior Notes, due 2018 [Member]
Debt Instrument [Line Items]
Senior notes	398	0
Unamortized debt discount and issuance costs	2
Senior Notes [Member] \| 3.3% Senior Notes, due 2020 [Member]
Debt Instrument [Line Items]
Senior notes	695	0
Unamortized debt discount and issuance costs	5
Senior Notes [Member] \| 4.0% Senior Notes, due 2025 [Member]
Debt Instrument [Line Items]
Senior notes	690	0
Unamortized debt discount and issuance costs	10
Senior Notes [Member] \| 4.4% Senior Notes, due 2026 [Member]
Debt Instrument [Line Items]
Senior notes	890	0
Unamortized debt discount and issuance costs	10
Senior Notes [Member] \| 6.55% Senior Notes, due 2037 [Member]
Debt Instrument [Line Items]
Senior notes	396	$ 396
Unamortized debt discount and issuance costs	$ 4

Amount of short-term debt and current maturity of long-term debt and capital lease obligations due within one year or the normal operating cycle, if longer.

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 210.5-02.19,20)
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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

No definition available.

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The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28541-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Represents the aggregate of total long-term debt, including current maturities and short-term debt.

+ References

No definition available.

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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 FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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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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Carrying amount of long-term debt, net of unamortized discount or premium, excluding amounts to be repaid within one year or the normal operating cycle, if longer (current maturities). 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
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-Name Accounting Standards Codification
-Topic 210
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-Section S99
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- Definition

Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
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