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Summary of Stock Option Activity (Detail) - Predecessor - $ / shares
4 Months Ended 12 Months Ended
Jul. 31, 2017
Mar. 31, 2017
Stock-Based Compensation And Incentive Plans [Abstract]    
Weighted-average Exercise Price Beginning Balance Outstanding $ 28.14 $ 31.73
Weighted-average Exercise Price, Expired or cancelled/forfeited $ 28.14 44.86
Weighted-average Exercise Price, Ending Balance Outstanding   $ 28.14
Number of Shares Outstanding    
Number of Shares Beginning Balance Outstanding 1,395,548 1,777,124
Number of Shares, Expired or cancelled/forfeited (1,395,548) (381,576)
Number of Shares Ending Balance Outstanding   1,395,548