Business Combinations (Narrative) (Details) $ in Millions	6 Months Ended
	Mar. 31, 2018 USD ($)
Business Acquisition [Line Items]
Business combinations, goodwill acquired during period	$ 62.9
2018 Acquisitions
Business Acquisition [Line Items]
Number of acquisitions completed	5
Aggregate purchase price, net of cash acquired	$ 281.0
Business combinations, recognized property, plant, and equipment	168.9
Business combinations, goodwill acquired during period	62.9
Business combinations, tax deductible goodwill	3.0
Business combinations, recognized identifiable intangible assets	$ 65.3
Acquired finite-lived intangible assets, weighted-average useful life	12 years