Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ (68,086)	$ (66,655)	$ (68,979)	$ 941
Other comprehensive income (loss):
Foreign currency translation adjustment	1,520	(2,028)	(2,390)	(1,971)
Total other comprehensive income (loss)	1,520	(2,028)	(2,390)	(1,971)
Comprehensive income (loss)	$ (66,566)	$ (68,683)	$ (71,369)	$ (1,030)