Acquisitions, Dispositions, Goodwill and Other Intangible Assets (Variable Interest Entity) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Current Assets	$ 1,811
Variable Interest Entity, Consolidated, Carrying Amount, Noncurrent Assets	1,096
Variable Interest Entity, Consolidated, Carrying Amount, Assets	2,907
Variable Interest Entity, Consolidated, Carrying Amount, Current Liabilities	1,990
Variable Interest Entity, Consolidated, Carrying Amount, Noncurrent Liabilities	1,123
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	$ 3,113

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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Namespace Prefix:	us-gaap_
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_
Data Type:	xbrli:monetaryItemType
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