XML 78 R62.htm IDEA: XBRL DOCUMENT v3.7.0.1
Post Retirement Benefit Plans - Additional Information (Detail) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Nov. 30, 2016
Apr. 30, 2017
Apr. 30, 2016
Apr. 30, 2017
Apr. 30, 2016
Nov. 03, 2016
Postemployment Benefits [Abstract]            
Annuity contract       $ 49.2    
Lump sum payments made to participants   $ 3.8   38.9    
Decrease in projected benefit obligation       88.1    
Pension settlement charge   $ 1.1 $ 0.0 24.6 $ 0.0  
Reduction in projected benefit obligation $ 21.3          
Discount rate 4.20%         3.82%
Company's pension contributions       $ 5.1 $ 6.2