Segment and Geographic Information - Segments (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting Information [Line Items]
Sales	$ 248.4	$ 242.7	$ 233.5	$ 245.5	$ 232.4	$ 263.0	$ 258.8	$ 255.1	$ 970.1	$ 1,009.3	$ 942.5
Operating Income (Loss)	63.0	67.4	67.9	80.6	47.9	63.1	61.4	49.6	278.9	222.0	161.2
Business separation, restructuring and cost reduction actions	(2.5)	(1.1)	1.8	0.9	(7.1)	(8.6)	(1.7)	(4.2)	(0.9)	(21.6)	(1.3)
Depreciation and Amortization									46.9	56.9	59.5
Equity Affiliates’ Income	0.0	$ 0.0	$ 0.0	$ 0.2	0.3	$ 0.0	$ 0.4	$ 0.3	0.2	1.0	1.7
Total Assets	1,043.8				887.4				1,043.8	887.4	1,034.0
Investment in Net Assets of and Advances to Equity Affiliates	0.0				12.5				0.0	12.5	14.1
Expenditures for Long-Lived Assets									35.8	22.1	24.3
Operating Segments
Segment Reporting Information [Line Items]
Operating Income (Loss)									279.8	243.6	162.5
Operating Segments | Materials
Segment Reporting Information [Line Items]
Sales									756.7	743.4	640.0
Operating Income (Loss)									252.3	213.7	124.6
Business separation, restructuring and cost reduction actions										(12.3)
Depreciation and Amortization									44.4	48.1	52.7
Equity Affiliates’ Income									0.2	1.0	1.7
Total Assets	733.4				754.8				733.4	754.8	828.1
Investment in Net Assets of and Advances to Equity Affiliates	0.0				12.5				0.0	12.5	14.1
Expenditures for Long-Lived Assets									34.4	21.2	17.9
Operating Segments | Delivery Systems and Services
Segment Reporting Information [Line Items]
Sales									213.4	265.9	302.5
Operating Income (Loss)									50.8	49.1	57.6
Business separation, restructuring and cost reduction actions										(5.8)
Depreciation and Amortization									2.1	8.3	6.3
Total Assets	104.0				92.7				104.0	92.7	137.0
Expenditures for Long-Lived Assets									0.7	0.8	6.0
Operating Segments | Corporate
Segment Reporting Information [Line Items]
Operating Income (Loss)									(23.3)	(19.2)	(19.7)
Depreciation and Amortization									0.4	0.5	0.5
Total Assets	$ 206.4				$ 39.9				206.4	39.9	68.9
Expenditures for Long-Lived Assets									0.7	0.1	0.4
Segment Reconciling Items
Segment Reporting Information [Line Items]
Business separation, restructuring and cost reduction actions									$ (0.9)	$ (21.6)	$ (1.3)