Balance Sheet Accounts - Schedule of Other Current Assets, net (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Other Current Assets [Line Items]
Recoverable from the U.S. government for acquisition related integration costs	$ 11.9	$ 11.9
Recoverable from the U.S. government for competitive improvement program obligations (see Note 10)	20.5	7.6
Prepaid expenses	16.4	16.5
Receivables, net	6.5	17.8
Income taxes receivable	5.8	26.8
Other	6.2	5.6
Other current assets, net	72.8	91.7
United Technologies Corporation
Other Current Assets [Line Items]
Receivables, net	$ 5.5	$ 5.5