Fair Value - Additional Information (Details) - Estimate of Fair Value Measurement - Level 2 - USD ($) $ in Millions	Mar. 31, 2020	Sep. 30, 2019
Tranche A term loan
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	$ 820.1
Tranche B term loan
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	$ 1,200.0
Senior Notes | Notes payable | Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value		$ 385.0