v3.7.0.1
Related Party Transactions (Detail) - USD ($)
$ in Millions
1 Months Ended 3 Months Ended
Jan. 31, 2014
Apr. 30, 2017
Apr. 30, 2016
Related Party Transaction [Line Items]      
Term of agreements (in years) 95 years    
Management      
Related Party Transaction [Line Items]      
Term of agreements (in years)   10 years  
Total rent due under agreements fiscal year end January 31, 2018   $ 9  
Total rent due under agreements   91  
Rent expense   $ 2 $ 2