Revenue Recognition - Disaggregation of Revenue by Operating Segment and by Geographic Region (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Sales	$ 1,657.2	$ 1,651.2	$ 3,299.5	$ 3,237.8
North America
Disaggregation of Revenue [Line Items]
Sales	987.1		1,985.9
Europe, Middle East and Africa (EMEA)
Disaggregation of Revenue [Line Items]
Sales	331.1		625.5
Asia Pacific
Disaggregation of Revenue [Line Items]
Sales	214.7		429.1
Latin America
Disaggregation of Revenue [Line Items]
Sales	124.3		259.0
Architecture & Software
Disaggregation of Revenue [Line Items]
Sales	739.7		1,492.8
Architecture & Software | North America
Disaggregation of Revenue [Line Items]
Sales	423.1		865.9
Architecture & Software | Europe, Middle East and Africa (EMEA)
Disaggregation of Revenue [Line Items]
Sales	176.0		331.5
Architecture & Software | Asia Pacific
Disaggregation of Revenue [Line Items]
Sales	97.8		199.1
Architecture & Software | Latin America
Disaggregation of Revenue [Line Items]
Sales	42.8		96.3
Control Products & Solutions
Disaggregation of Revenue [Line Items]
Sales	917.5		1,806.7
Control Products & Solutions | North America
Disaggregation of Revenue [Line Items]
Sales	564.0		1,120.0
Control Products & Solutions | Europe, Middle East and Africa (EMEA)
Disaggregation of Revenue [Line Items]
Sales	155.1		294.0
Control Products & Solutions | Asia Pacific
Disaggregation of Revenue [Line Items]
Sales	116.9		230.0
Control Products & Solutions | Latin America
Disaggregation of Revenue [Line Items]
Sales	$ 81.5		$ 162.7