Credit Quality of Long-term Receivables (Reserve and Additional Information) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2014	Dec. 31, 2013
Notes to Condensed Consolidated Financial Statements [Abstract]
Financing Receivable Reserve For Credit Losses And Exposure	$ (18)	$ (49)
Percentage Long Term Receivables High Credit Risk	8.00%	9.00%

A valuation allowance for financing receivables that are expected to be uncollectible and/or contain collateral exposure risk.

No definition available.

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