Business Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2012	Mar. 31, 2011
Sales and operating results of reportable segments
Sales	$ 1,561.1	$ 1,464.1	$ 3,035.0	$ 2,829.9
Net income	167.8	166.4	351.1	316.5
Business Segment information (Textual) [Abstract]
Portion of total sales to largest distributor	10.00%	10.00%	10.00%	10.00%
Total Segments [Member]
Sales and operating results of reportable segments
Net income	268.3	244.2	552.1	466.2
Architecture and Software [Member]
Sales and operating results of reportable segments
Sales	664.8	624.2	1,315.3	1,238.1
Net income	167.7	152.2	354.0	305.3
Control Products and Solutions [Member]
Sales and operating results of reportable segments
Sales	896.3	839.9	1,719.7	1,591.8
Net income	100.6	92.0	198.1	160.9
Purchase accounting depreciation and amortization [Member]
Sales and operating results of reportable segments
Net income	(4.9)	(4.7)	(9.9)	(9.5)
General corporate - net [Member]
Sales and operating results of reportable segments
Net income	(25.1)	(20.5)	(46.0)	(36.2)
Interest expense [Member]
Sales and operating results of reportable segments
Net income	(15.0)	(15.4)	(30.0)	(30.2)
Income tax provision [Member]
Sales and operating results of reportable segments
Net income	$ (55.5)	$ (37.2)	$ (115.1)	$ (73.8)