Revenue from Contracts with Customers - Disaggregated By Geographic Location (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Total revenue	$ 220,227	$ 198,390	$ 430,727	$ 377,757
North America
Disaggregation of Revenue [Line Items]
Total revenue	85,887	83,156	166,118	152,053
Asia/Pacific/Other
Disaggregation of Revenue [Line Items]
Total revenue	105,014	77,653	208,553	157,112
United Kingdom
Disaggregation of Revenue [Line Items]
Total revenue	10,384	12,540	20,305	24,618
Rest of Europe
Disaggregation of Revenue [Line Items]
Total revenue	$ 18,942	$ 25,041	$ 35,751	$ 43,974