XML 48 R39.htm IDEA: XBRL DOCUMENT v3.19.1
Defined Benefit Pension Plans - Additional Information (Detail) - USD ($)
9 Months Ended
Jan. 31, 2019
Jan. 31, 2018
Retirement Benefits [Abstract]    
Employer contributions paid during the remainder of fiscal year $ 0  
Employer contributions $ 1,000,000 $ 600,000
Assumed as expected long-term rate of return 7.75% 7.75%