Summary of Performance Based RSU Awards (Parenthetical) (Detail)		12 Months Ended
	Dec. 05, 2017	Jul. 31, 2017	Jul. 31, 2016
Series Award One
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected Percentage of Vesting		184.00%	196.00%
Series Award Three
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected Percentage of Vesting	100.00%		151.00%
Series Award Four | Tranche One
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected Percentage of Vesting	100.00%	100.00%
Series Award Four | Second Tranche
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected Percentage of Vesting	172.00%	184.00%