Revenue (Contract Assets and Liabilities) (Details) - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Sep. 30, 2020	Sep. 30, 2019
Revenue from Contract with Customer [Abstract]
Contract liabilities	$ 36,915	$ 30,841	$ 26,259	$ 39,051
Change in Contract with Customer, Asset [Roll Forward]
beginning of period	80,759	73,467
Recognized in current period	232,750	255,623
Reclassified to accounts receivable	244,766	253,199
Amounts related to sale of the Memcor product line	0	2,710
Foreign currency	600	(1,011)
end of period	69,343	77,590
Change in Contract with Customer, Liability [Roll Forward]
Recognized in current period	245,049	241,468
Amounts in beginning balance reclassified to revenue	(18,496)	(37,508)
Current period amounts reclassified to revenue	(216,972)	(210,985)
Amounts related to sale of the Memcor product line	0	(700)
Foreign currency	$ 1,075	$ (485)