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Intangible Assets - Additional Information (Detail) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Mar. 31, 2021
Mar. 31, 2020
Mar. 31, 2021
Mar. 31, 2020
Intangible Assets Net Excluding Goodwill [Abstract]        
Amortization expense recognized $ 0.3 $ 0.4 $ 0.6 $ 0.7
Amortization expense for remainder of 2021 0.6   0.6  
Amortization expense for 2022 1.0   1.0  
Amortization expense for 2023 0.9   0.9  
Amortization expense for 2024 0.8   0.8  
Amortization expense for 2025 $ 0.7   $ 0.7  
Remaining weighted average term of intangible assets     14 years 7 months 6 days