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Commitments and Contingencies - Additional Information (Details) - USD ($)
$ in Millions
6 Months Ended
Oct. 31, 2020
Sep. 14, 2020
Jun. 28, 2020
Apr. 27, 2020
Apr. 30, 2021
Commitments And Contingencies [Line Items]          
Recorded unconditional purchase obligation         $ 73.9
Loss contingency, damages sought $ 880.0        
Accounts receivable outstanding         8.0
Posco Energy [Member]          
Commitments And Contingencies [Line Items]          
Loss contingency, damages sought     $ 200.0 $ 3.3  
Unspecified warranty claims       7.0  
License termination       $ 110.0  
Bond amount         $ 46.0
Loss contingency, claimed Loss   $ 1.0