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Goodwill and Intangible Assets - Additional Information (Detail) - USD ($)
$ in Millions
3 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Goodwill And Intangible Assets [Line Items]    
Amortization expense estimated for year one $ 8  
Amortization expense estimated for year two 8  
Amortization expense estimated for year three 8  
Amortization expense estimated for year four 8  
Amortization expense estimated for year five 8  
Cost of Sales, Selling and Administrative Expenses and Research and Technical Expenses [Member]    
Goodwill And Intangible Assets [Line Items]    
Amortization of intangible assets $ 2 $ 1
Minimum [Member]    
Goodwill And Intangible Assets [Line Items]    
Useful life of intangible assets 10 years  
Maximum [Member]    
Goodwill And Intangible Assets [Line Items]    
Useful life of intangible assets 25 years  
Weighted Average [Member]    
Goodwill And Intangible Assets [Line Items]    
Useful life of intangible assets 18 years