Fair Value Measurements - Narrative (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Apr. 30, 2018	Sep. 30, 2018	Sep. 30, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Useful life		3 years
Trademarks and tradenames	$ 7.9	$ 7.9	$ 16.2
Trademarks and tradenames
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Useful life	3 years