Business Segment Information - Schedule of Sales and Property by Geographic Region (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Sales and property by geographic region
Sales	$ 1,729.5	$ 1,698.7	$ 1,651.2	$ 1,586.6	$ 1,667.5	$ 1,599.2	$ 1,554.3	$ 1,490.3	$ 6,666.0	$ 6,311.3	$ 5,879.5
Property	576.8				583.9				576.8	583.9	578.3
United States
Sales and property by geographic region
Sales									3,602.6	3,458.4	3,213.4
Property	437.6				443.4				437.6	443.4	445.4
Canada
Sales and property by geographic region
Sales									361.5	343.4	316.4
Property	12.6				8.8				12.6	8.8	7.3
Europe, Middle East and Africa
Sales and property by geographic region
Sales									1,286.8	1,193.7	1,147.2
Property	53.3				52.5				53.3	52.5	49.9
Asia Pacific
Sales and property by geographic region
Sales									933.3	866.4	764.4
Property	42.9				40.0				42.9	40.0	37.4
Latin America
Sales and property by geographic region
Sales									481.8	449.4	438.1
Property	$ 30.4				$ 39.2				$ 30.4	$ 39.2	$ 38.3