Shareholders' Equity - Additional Information (Detail) - USD ($)	3 Months Ended	9 Months Ended
	Jan. 30, 2016	Jan. 30, 2016	Oct. 20, 2015	May. 02, 2015	Jan. 31, 2015
Class of Stock [Line Items]
Stock repurchased, shares	1,798,962	1,799,000
Stock repurchased, value	$ 16,489,000	$ 16,489,000
Stock repurchase program, remaining authorized repurchase amount	$ 33,511,000	$ 33,511,000
Treasury stock, shares	36,797,000	36,797,000		34,841,000	34,580,000
Treasury stock, at cost	$ 1,098,645,000	$ 1,098,645,000		$ 1,079,716,000	$ 1,073,424,000
Maximum
Class of Stock [Line Items]
Number of shares authorized to be repurchase			$ 50,000,000
Stock Repurchase Program
Class of Stock [Line Items]
Treasury stock, shares	36,797,336	36,797,336
Treasury stock, at cost	$ 1,082,156,000	$ 1,082,156,000