Quarterly report pursuant to Section 13 or 15(d)

Significant Accounting Policies - Revenue by Major Customers (Detail)

v3.20.1
Significant Accounting Policies - Revenue by Major Customers (Detail) - Revenues - Customer Concentration Risk
3 Months Ended 6 Months Ended
Mar. 31, 2020
Mar. 31, 2019
Mar. 31, 2020
Mar. 31, 2019
Private        
Concentration Risk [Line Items]        
Concentration risk percentage 39.40% 30.70% 39.40% 31.40%
Public        
Concentration Risk [Line Items]        
Concentration risk percentage 60.60% 69.30% 60.60% 68.60%