Employee Benefit Plans - Fair Value, Investments, Entities that Calculate Net Asset Value Per Share (Details) - USD ($) $ in Millions		12 Months Ended
		Sep. 30, 2020	Sep. 30, 2019
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Redemption Notice Period	[1]	15 days	15 days
Pension Plan, Defined Benefit
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Fair Value		$ 227.5	$ 213.2

[1] Represents the maximum redemption period. A portion of the investment does not have any redemption period restrictions.