Reconciliation of Basic and Diluted Income (Loss) Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Jan. 27, 2018	Jan. 28, 2017	Jan. 27, 2018	Jan. 28, 2017
Numerator for basic income (loss) per share:
Net income (loss)	$ (63,536)	$ 70,276	$ (104,408)	$ 35,451
Less allocation of dividends to participating securities	(21)	(168)	(59)	(559)
Less allocation of undistributed earnings to participating securities		(948)		(42)
Net income (loss) available to common shareholders	(63,557)	69,160	(104,467)	34,850
Numerator for diluted income (loss) per share:
Net income (loss) available to common shareholders	(63,557)	69,160	(104,467)	34,850
Allocation of undistributed earnings to participating securities		948		42
Less diluted allocation of undistributed earnings to participating securities		(946)		(42)
Net income (loss) available to common shareholders	$ (63,557)	$ 69,162	$ (104,467)	$ 34,850
Denominator for basic income (loss) per share:
Basic weighted average common shares	72,649	71,581	72,566	72,232
Denominator for diluted income (loss) per share:
Basic weighted average common shares	72,649	71,581	72,566	72,232
Average dilutive options		68		77
Average dilutive non-participating securities		65		78
Diluted weighted average common shares	72,649	71,714	72,566	72,387
Income (loss) per common share:
Basic	$ (0.87)	$ 0.97	$ (1.44)	$ 0.48
Diluted	$ (0.87)	$ 0.96	$ (1.44)	$ 0.48