Acquisitions, Dispositions, Goodwill and Other Intangible Assets (Variable Interest Entity) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Current Assets	$ 1,482
Variable Interest Entity, Consolidated, Carrying Amount, Current Liabilities	1,678
Variable Interest Entity, Consolidated, Carrying Amount, Noncurrent Assets	961
Variable Interest Entity, Consolidated, Carrying Amount, Assets	2,443
Variable Interest Entity, Consolidated, Carrying Amount, Noncurrent Liabilities	983
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	$ 2,661

The carrying amount of the consolidated Variable Interest Entity's assets included in the reporting entity's statement of financial position.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (bb)

-URI http://asc.fasb.org/extlink&oid=28200181&loc=d3e5710-111685

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The carrying amount of the consolidated Variable Interest Entity's liabilities included in the reporting entity's statement of financial position.

+ References

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	credit
Period Type:	instant

- Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The carrying amount of the consolidated Variable Interest Entity's current assets included in the reporting entity's statement of financial position.

+ References

No definition available.

+ Details

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Namespace Prefix:	utx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The carrying amount of the consolidated Variable Interest Entity's current liabilities included in the reporting entity's statement of financial position.

+ References

No definition available.

+ Details

Name:	utx_VariableInterestEntityConsolidatedCarryingAmountCurrentLiabilities
Namespace Prefix:	utx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The carrying amount of the consolidated Variable Interest Entity's noncurrent assets included in the reporting entity's statement of financial position.

+ References

No definition available.

+ Details

Name:	utx_VariableInterestEntityConsolidatedCarryingAmountNoncurrentAssets
Namespace Prefix:	utx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The carrying amount of the consolidated Variable Interest Entity's noncurrent liabilities included in the reporting entity's statement of financial position.

+ References

No definition available.

+ Details

Name:	utx_VariableInterestEntityConsolidatedCarryingAmountNoncurrentLiabilities
Namespace Prefix:	utx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant