Long-Term Financing Receivables (Reserve and Additional Information) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Receivables [Abstract]
Long Term Receivables High Credit Risk Percentage	7.00%	7.00%
Financing Receivable Reserve For Credit Losses And Exposure	$ 10	$ 10

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