Shareowners' Equity and Noncontrolling Interest Shareowners' Equity and Noncontrolling Interest (Accelerated Stock Repurchase) (Details) (USD $)	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
ASR Aggregate Purchase Price	$ 2,650,000,000utx_ASRAggregatePurchasePrice
ASR Shares Repurchased	18,600,000us-gaap_TreasuryStockSharesAcquired
ASR, Initial Price Paid Per Share	$ 121.24
ASR, Reduction to Shareowner's Equity	3,000,000,000	335,000,000
Accelerated Stock Repurchase [Member]
ASR amount included in APIC to be reclassified to treasury stock	398,000,000
ASR, Reduction to Shareowner's Equity	$ 2,250,000,000

The price paid per share to immediately purchase the targeted number of shares on the date of executing the accelerated share repurchase agreement.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 30

-Section 25

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6405686&loc=d3e22802-112653

+ Details

Name:	us-gaap_AcceleratedShareRepurchasesInitialPricePaidPerShare
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of shares that have been repurchased during the period and are being held in treasury.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29, 30

-Article 5

+ Details

Name:	us-gaap_TreasuryStockSharesAcquired
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 30

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6405813&loc=d3e23239-112655

+ Details

Name:	us-gaap_TreasuryStockValueAcquiredCostMethod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Aggregate purchase price to repurchase shares of common stock per the ASR agreement

+ References

No definition available.

+ Details

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

- Definition

ASR amount included in Additional Paid in Capital to be reclassified to treasury stock

+ References

No definition available.

+ Details

Name:	utx_ASRamountincludedinAPICtobereclassifiedtotreasurystock
Namespace Prefix:	utx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	utx_StatementEquityAndRedeemableNoncontrollingInterestComponentsAxis=utx_AcceleratedStockRepurchaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: