Debt - Components of Debt (Detail) - USD ($)	Jun. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Debt and capital lease obligations	$ 9,057,000,000	$ 9,310,000,000
Current portion of long-term debt	390,000,000	417,000,000
Long-term debt, less current portion	8,667,000,000	8,893,000,000
Domestic Line of Credit [Member]
Debt Instrument [Line Items]
Debt and capital lease obligations	0	426,000,000
Commercial Paper [Member]
Debt Instrument [Line Items]
Debt and capital lease obligations	253,000,000
Foreign Line of Credit [Member]
Debt Instrument [Line Items]
Debt and capital lease obligations	171,000,000	239,000,000
Senior Notes [Member]
Debt Instrument [Line Items]
Debt and capital lease obligations	6,033,000,000	6,033,000,000
Tax-exempt Bonds [Member]
Debt Instrument [Line Items]
Debt and capital lease obligations	2,305,000,000	2,304,000,000
Current portion of long-term debt	148,000,000
Capital Leases and Other [Member]
Debt Instrument [Line Items]
Debt and capital lease obligations	$ 295,000,000	$ 308,000,000

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 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.13,16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: 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

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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.

+ 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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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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