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Income Taxes - Additional Information (Detail) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Dec. 31, 2017
Apr. 30, 2020
Apr. 30, 2019
Apr. 30, 2020
Apr. 30, 2019
Oct. 31, 2019
Oct. 31, 2018
Income Tax Disclosure [Abstract]              
Income tax expense (benefit)   $ (10.1) $ 2.5 $ (12.7) $ (1.9)    
Pre-tax (income) loss   56.10% (30.80%) 42.50% 17.80%    
Net discrete tax expense (benefit) related to net operating loss carrybacks   $ (5.7)   $ (5.4)      
Net discrete tax expense (benefit) related to share-based compensation     $ 0.4   $ 0.8    
Net operating loss carryforwards             $ 3.5
Estimate income tax effects due to CARES Act   3.5          
Federal statutory income tax rate 35.00%     21.00%      
Unrecognized tax benefits   2.7   $ 2.7   $ 2.6  
Unrecognized tax benefits that would affect the annual effective income tax rate if recognized   $ 0.4   $ 0.4