Segment and Geographic Information - Total Revenues by Geographic Location (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Total revenues	$ 60,856.1	$ 66,036.0	$ 42,534.2
Operating revenues	2,914.1	2,107.4	1,673.1
Long-lived assets	123.5	112.9	93.3
United States
Total revenues	6,017.4	5,102.3	3,313.1
Operating revenues	2,120.4	1,448.2	1,157.4
Long-lived assets	76.0	67.9	54.1
Europe
Total revenues	3,498.9	3,440.2	1,889.6
Operating revenues	494.3	474.6	371.3
Long-lived assets	40.7	41.1	36.0
South America
Total revenues	271.4	87.2	64.5
Operating revenues	127.0	87.2	64.5
Long-lived assets	4.4	2.9	2.1
Middle East and Asia
Total revenues	51,023.6	57,395.5	37,259.1
Operating revenues	127.6	86.6	72.0
Long-lived assets	2.4	1.0	0.9
Other
Total revenues	44.8	10.8	7.9
Operating revenues	44.8	10.8	7.9
Long-lived assets	$ 0.0	$ 0.0	$ 0.2