Revenue Recognition - Summary of Revenues Classified by Major Geographic Region (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Revenues:
Total net revenues	$ 86,495	$ 70,304	$ 163,954	$ 142,788
United States
Revenues:
Total net revenues	36,505	29,630	71,546	67,694
Other Americas
Revenues:
Total net revenues		278	8	632
Germany
Revenues:
Total net revenues	20,102	15,114	40,319	28,830
Other Europe, Middle East and Africa
Revenues:
Total net revenues	8,628	5,360	13,225	10,144
Japan
Revenues:
Total net revenues	15,518	7,985	26,929	17,738
Other Asia-Pacific
Revenues:
Total net revenues	$ 5,742	$ 11,937	$ 11,927	$ 17,750