Company Overview - Additional Information (Detail)	12 Months Ended
	Sep. 30, 2020 State Province
Company Overview [Line Items]
Date of incorporation	Aug. 22, 1997
U.S. [Member]
Company Overview [Line Items]
Number of states in which entity operates | State	50
Canada [Member]
Company Overview [Line Items]
Number of provinces in which entity operates | Province	6