Balance Sheet Accounts - Schedule of Other Current Assets, net (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015	Nov. 30, 2015	Feb. 28, 2015
Other Current Assets [Line Items]
Prepaid expenses	$ 10.7	$ 11.9	$ 10.7
Recoverable from the U.S. government for Competitive Improvement Program severance obligations	10.0	9.1	9.5
Receivables, net	14.4	10.6	7.2
Income taxes receivable	1.6	1.6	2.9	$ 2.3
Indemnification receivable from UTC	182.3	169.5	171.5	190.0
Other	6.5	8.4	6.5
Other current assets, net	70.8	69.2	64.4	$ 43.7
Recoverable Of Restructuring Costs	30.6	33.1	34.3
UTC [Member]
Other Current Assets [Line Items]
Indemnification receivable from UTC	15.7	15.7	15.7
Business Integration Costs [Member]
Other Current Assets [Line Items]
Recoverable from the U.S. government for Rocketdyne Business integration costs	$ 11.9	$ 11.9	$ 11.9