Business Separation, Restructuring, and Cost Reduction Actions (Narrative) (Details) $ in Millions	1 Months Ended	3 Months Ended									12 Months Ended
	Jan. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2016 USD ($) position	Sep. 30, 2015 USD ($) position	Sep. 30, 2014 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring charge net of business separation costs										$ 1.3	$ (0.7)	$ 21.6	$ 1.3
Number of positions eliminated | position											90	260
Carrying value of assets		$ 17.9									$ 17.9
Restructuring charge		$ 2.5	$ 1.1	$ (1.8)	$ (0.9)	$ 7.1	$ 8.6	$ 1.7	$ 4.2		0.9	$ 21.6	1.3
Operating Segments | Materials
Restructuring Cost and Reserve [Line Items]
Restructuring charge												12.3
Operating Segments | Delivery Systems and Services
Restructuring Cost and Reserve [Line Items]
Restructuring charge												5.8
Corporate, Non-Segment
Restructuring Cost and Reserve [Line Items]
Restructuring charge												3.5
Onsite Ammonia Plant
Restructuring Cost and Reserve [Line Items]
Gain from sale of plants				1.4
Proceeds from sale of plants	$ 17.1			$ 17.1
Severance
Restructuring Cost and Reserve [Line Items]
Restructuring charge net of business separation costs											2.5	14.4	1.3
Asset actions
Restructuring Cost and Reserve [Line Items]
Restructuring charge net of business separation costs											(3.2)	$ 7.2	$ 0.0
Separation
Restructuring Cost and Reserve [Line Items]
Costs incurred from separation											$ 1.6