Goodwill and Intangible Assets - (Details) - USD ($)	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
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	$ 1,600,000	$ 2,200,000	3,300,000	$ 4,600,000
Goodwill, increased from effects of foreign currency exchange rates			$ 4,600,000