Cost Reduction Plan - Narrative (Details) $ in Millions		1 Months Ended	3 Months Ended
	Jan. 30, 2014 employee	Dec. 31, 2015 USD ($)	Mar. 31, 2016 USD ($)	Aug. 31, 2015 USD ($)	May. 31, 2015 USD ($) employee	Feb. 28, 2015 USD ($) employee	Nov. 30, 2014 USD ($) employee	Feb. 28, 2014 USD ($)
Restructuring Cost and Reserve [Line Items]
Reduction in headcount of employees | employee	260				500	60	90
Restructuring plan, liability						$ 4.1	$ 4.3	$ 10.0
Restructuring plan cost							6.3
Reduction in restructuring plan liability				$ 1.5	$ 5.1
Period estimated to incur restructuring and related costs			4 years
Estimated restructuring and related costs over next four years			$ 110.0
Non-cash accelerated depreciation expense due to CIP		$ 0.1	$ 0.2
Postemployment benefits liability				$ 2.6
Severance costs		$ 2.4
Other Noncurrent Assets [Member] | Rocketdyne Business [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring plan cost							$ 3.0