Goodwill and Intangible Assets - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Goodwill [Line Items]
Goodwill impairment loss	$ 41,300	$ 41,340
Impairment of long-lived assets	1,100
Definite-lived intangible assets, amortization expense		$ 11,200	$ 7,800	$ 5,800
Trade names | Mexico Reporting Unit
Goodwill [Line Items]
Impairment of intangible assets	2,900
Trade names | G P M X Reporting Unit
Goodwill [Line Items]
Impairment of intangible assets	$ 1,700