Revenue Recognition - Disaggregation of Revenue by Operating Segment and by Geographic Region (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
North America
Disaggregation of Revenue [Line Items]
Sales									3,760.2	4,014.3	3,964.1
Europe, Middle East and Africa
Disaggregation of Revenue [Line Items]
Sales									1,249.3	1,249.8	1,286.8
Asia Pacific
Disaggregation of Revenue [Line Items]
Sales									868.7	908.6	933.3
Latin America
Disaggregation of Revenue [Line Items]
Sales									451.6	522.1	$ 481.8
Architecture & Software
Disaggregation of Revenue [Line Items]
Sales									2,832.9	3,021.9
Architecture & Software | North America
Disaggregation of Revenue [Line Items]
Sales									1,641.7	1,752.1
Architecture & Software | Europe, Middle East and Africa
Disaggregation of Revenue [Line Items]
Sales									606.8	654.2
Architecture & Software | Asia Pacific
Disaggregation of Revenue [Line Items]
Sales									419.7	426.4
Architecture & Software | Latin America
Disaggregation of Revenue [Line Items]
Sales									164.7	189.2
Control Products & Solutions
Disaggregation of Revenue [Line Items]
Sales									3,496.9	3,672.9
Control Products & Solutions | North America
Disaggregation of Revenue [Line Items]
Sales									2,118.5	2,262.2
Control Products & Solutions | Europe, Middle East and Africa
Disaggregation of Revenue [Line Items]
Sales									642.5	595.6
Control Products & Solutions | Asia Pacific
Disaggregation of Revenue [Line Items]
Sales									449.0	482.2
Control Products & Solutions | Latin America
Disaggregation of Revenue [Line Items]
Sales									$ 286.9	$ 332.9