Financial Instruments (Contractual Maturity Date of Marketable Debt Securities) (Details) $ in Millions	Sep. 30, 2015 USD ($)
Fair Value Disclosures [Abstract]
Due in 1 year	$ 8,525
Due in 1 year through 5 years	27,725
Due in 5 years through 10 years	7,244
Due after 10 years	10,024
Total	$ 53,518

Fair value of available-for-sale debt securities maturing in the sixth fiscal year through the tenth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 320

-Section 50

-Paragraph 3

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6957658&loc=d3e62586-112803

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-Name Accounting Standards Codification

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- Definition

Fair value of available-for-sale debt securities maturing in the second fiscal year through the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

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-Paragraph 3

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-URI http://asc.fasb.org/extlink&oid=6957658&loc=d3e62586-112803

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

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-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563

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Fair value of available-for-sale debt securities maturing after the tenth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

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-URI http://asc.fasb.org/extlink&oid=6957658&loc=d3e62586-112803

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- Definition

Fair value of available-for-sale debt securities maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

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Amount of debt securities categorized neither as held-to-maturity nor trading.

+ References

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-Name Accounting Standards Codification

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