Segment and Geographic Information - Total Revenues by Geographic Location (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Total revenues	$ 42,534.2	$ 54,139.6	$ 32,897.0
Operating revenues:	1,673.1	1,308.3	1,106.1
Long-lived assets, as defined:	93.3	62.1	43.9
United States
Total revenues	3,313.1	2,223.3	1,947.6
Operating revenues:	1,157.4	928.3	799.4
Long-lived assets, as defined:	54.1	55.4	33.9
Europe
Total revenues	1,889.6	532.6	280.2
Operating revenues:	371.3	237.9	209.6
Long-lived assets, as defined:	36.0	3.1	6.6
South America
Total revenues	64.5	58.9	56.5
Operating revenues:	64.5	58.9	56.5
Long-lived assets, as defined:	2.1	2.1	2.1
Middle East and Asia
Total revenues	37,259.1	51,317.1	30,606.9
Operating revenues:	72.0	75.5	34.8
Long-lived assets, as defined:	0.9	1.3	1.0
Other
Total revenues	7.9	7.7	5.8
Operating revenues:	7.9	7.7	5.8
Long-lived assets, as defined:	$ 0.2	$ 0.2	$ 0.3