Goodwill and Intangible Assets - (Details) - USD ($)	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
Impairment losses in connection with the goodwill			$ 0	$ 0
Impairment losses in connection with the intangible assets			0	0
Amortization expense related to other intangible assets	$ 2,200,000	$ 2,900,000	4,600,000	$ 5,700,000
Other intangible assets recorded in asset acquisitions			1,400,000
Goodwill, changes in foreign currency exchange rates			$ 1,700,000