Commitments and Contingencies (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2024	Sep. 30, 2023
Loss Contingencies [Line Items]
Loss contingency, range of possible loss, portion not accrued	$ 10.0
Loss contingency accrual	3.8
Purchase obligation, due in next twelve months	57,592.2
Purchase obligation, due in second and third year	810.0
Purchase obligation, due in fourth and fifth year	78.5
Purchase obligation, due after fifth year	126.2
Purchase obligation, due in next twelve months	$ 56,275.9
Percentage of stop loss actual estimated claims (as a percent)	120.00%
Self insurance reserve and dental claims	$ 2.2	$ 1.9
Gain Capital Holdings Inc
Loss Contingencies [Line Items]
Loss contingency accrual, current	$ 31.1

Self Insurance, Stop Loss Coverage, Claims Threshold, Percent

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