Debt - Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
Sep. 30, 2016	Jun. 30, 2016
Debt Instrument [Line Items]
Commercial paper	$ 14,500,000,000	$ 12,900,000,000
Credit facility, financial covenant	As of September 30, 2016, we were in compliance with the only financial covenant in both credit agreements, which requires us to maintain a coverage ratio of at least three times earnings before interest, taxes, depreciation, and amortization to interest expense, as defined in the credit agreements.
Credit facility, drawn	$ 0	0
Long-term debt	60,200,000,000	40,600,000,000
Long-term debt fair value	64,000,000,000	44,000,000,000
Unamortized discount and debt issuance costs	597,000,000	$ 392,000,000
Credit Facility Expire on November 1st 2016
Debt Instrument [Line Items]
Credit facility	$ 5,000,000,000
Credit facility, expiration date	Nov. 01, 2016
Credit Facility Expire on November 14th 2018
Debt Instrument [Line Items]
Credit facility	$ 5,000,000,000
Credit facility, expiration date	Nov. 14, 2018
Commercial paper
Debt Instrument [Line Items]
Commercial paper, weighted average interest rate	0.55%	0.43%
Commercial paper \| Lower Limit
Debt Instrument [Line Items]
Commercial paper, maturity term	47 days	1 day
Commercial paper \| Upper Limit
Debt Instrument [Line Items]
Commercial paper, maturity term	187 days	99 days

Carrying value as of the balance sheet date of short-term borrowings using unsecured obligations issued by banks, corporations and other borrowers to investors. The maturities of these money market securities generally do not exceed 270 days.

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)(a)(3))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
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-Section S99
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-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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- Definition

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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- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

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- Definition

Amount of unamortized debt discount (premium) and debt issuance costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399

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- Definition

Identification of whether the entity has been in compliance with any credit facility debt covenants during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. 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
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-Section S99
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- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

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- Definition

Amount of cash inflow from contractual arrangement with the lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6513228

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- Definition

Weighted average interest rate of short-term debt outstanding.

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