Revenue Recognition - Disaggregation of Revenue by Operating Segment and Major Types of Products (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Sales	$ 1,570.0	$ 1,394.0	$ 1,681.3	$ 1,684.5	$ 1,730.2	$ 1,665.1	$ 1,657.2	$ 1,642.3	$ 6,329.8	$ 6,694.8	$ 6,666.0
Products
Disaggregation of Revenue [Line Items]
Sales									4,240.6	4,491.0
Solutions & Services
Disaggregation of Revenue [Line Items]
Sales									2,089.2	2,203.8
Architecture & Software
Disaggregation of Revenue [Line Items]
Sales									2,832.9	3,021.9
Architecture & Software | Products
Disaggregation of Revenue [Line Items]
Sales									2,832.9	3,021.9
Architecture & Software | Solutions & Services
Disaggregation of Revenue [Line Items]
Sales									0.0	0.0
Control Products & Solutions
Disaggregation of Revenue [Line Items]
Sales									3,496.9	3,672.9
Control Products & Solutions | Products
Disaggregation of Revenue [Line Items]
Sales									1,407.7	1,469.1
Control Products & Solutions | Solutions & Services
Disaggregation of Revenue [Line Items]
Sales									$ 2,089.2	$ 2,203.8