Special Charges (Narrative) (Details) - USD ($)	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Restructuring Cost and Reserve [Line Items]
Special charge	$ 47,400,000	$ 41,500,000	$ 28,400,000
Restructuring charges	23,700,000	14,600,000
Global information technology transformation [Member]
Restructuring Cost and Reserve [Line Items]
Special charge	17,400,000	22,000,000
Facility Closing [Member] | Site Consolidation [Member]
Restructuring Cost and Reserve [Line Items]
Special charge	600,000	5,800,000	7,300,000
Other Restructuring [Member] | Business Optimization [Member]
Restructuring Cost and Reserve [Line Items]
Special charge	9,200,000	13,100,000	19,800,000
Other Restructuring [Member] | Global Restructuring Program [Member]
Restructuring Cost and Reserve [Line Items]
Special charge	12,000,000.0	15,900,000	1,300,000
Other Restructuring [Member] | Workforce Reduction Plan [Member]
Restructuring Cost and Reserve [Line Items]
Special charge	$ 25,600,000	$ 6,700,000
Architectural Products Business [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges			$ 29,600,000