Shareholders' Equity - Additional Information (Detail) - USD ($)	3 Months Ended
	Jul. 29, 2017	Jul. 30, 2016	Apr. 29, 2017	Mar. 15, 2017	Oct. 20, 2015
Class of Stock [Line Items]
Treasury stock repurchased, shares	0	830,583
Treasury stock repurchase plan		$ 9,743,000
Treasury stock, shares	39,558,000	38,845,000	39,497,000
Treasury stock, at cost	$ 1,121,526,000	$ 1,121,053,000	$ 1,121,071,000
Maximum
Class of Stock [Line Items]
Number of shares authorized to be repurchase				$ 50,000,000	$ 50,000,000
Stock Repurchase Program
Class of Stock [Line Items]
Treasury stock, shares	39,558,301,000
Treasury stock, at cost	$ 1,086,869,000
New Stock Repurchase Program
Class of Stock [Line Items]
Stock repurchase program, remaining authorized repurchase amount	$ 50,000,000