Financing Arrangements (Summary of Debt) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Long-term debt, including current maturities	$ 4,768	$ 4,436
Less current maturities	376	560
Total long-term debt	4,392	3,876
Senior note - 1.35%, maturing 2017
Debt Instrument [Line Items]
Long-term debt, including current maturities	0	$ 250
Stated interest rate		1.35%
Senior note - 1.65%, maturing 2017
Debt Instrument [Line Items]
Long-term debt, including current maturities	0	$ 300
Stated interest rate		1.65%
Senior note - 4.50%, maturing 2018
Debt Instrument [Line Items]
Long-term debt, including current maturities	$ 363	$ 327
Stated interest rate	4.50%
Senior note - 2.40%, maturing 2019
Debt Instrument [Line Items]
Long-term debt, including current maturities	$ 250	250
Stated interest rate	2.40%
Senior note - 0.625% maturing 2020
Debt Instrument [Line Items]
Long-term debt, including current maturities	$ 599	525
Stated interest rate	0.625%
Senior note - 4.85%, maturing 2021
Debt Instrument [Line Items]
Long-term debt, including current maturities	$ 300	300
Stated interest rate	4.85%
Senior note - 4.70%, maturing 2022
Debt Instrument [Line Items]
Long-term debt, including current maturities	$ 300	300
Stated interest rate	4.70%
Senior note - 3.70%, maturing 2023
Debt Instrument [Line Items]
Long-term debt, including current maturities	$ 250	250
Stated interest rate	3.70%
Senior note - 4.00%, maturing 2024
Debt Instrument [Line Items]
Long-term debt, including current maturities	$ 300	300
Stated interest rate	4.00%
Senior note - 3.70%, maturing 2025
Debt Instrument [Line Items]
Long-term debt, including current maturities	$ 350	350
Stated interest rate	3.70%
Senior note - 1.25% maturing 2026
Debt Instrument [Line Items]
Long-term debt, including current maturities	$ 594	517
Stated interest rate	1.25%
Senior note - 1.10% maturing 2027
Debt Instrument [Line Items]
Long-term debt, including current maturities	$ 713	0
Stated interest rate	1.10%
Senior note - 5.15% maturing 2043
Debt Instrument [Line Items]
Long-term debt, including current maturities	$ 249	249
Stated interest rate	5.15%
Senior note - 4.50% maturing 2046
Debt Instrument [Line Items]
Long-term debt, including current maturities	$ 496	496
Stated interest rate	4.50%
Other, net
Debt Instrument [Line Items]
Long-term debt, including current maturities	$ 4	$ 22

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

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(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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+ References

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(a)(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
-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

Reference 3: 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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+ 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 210.5-02.19,20)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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+ 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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