Stockholders' Equity - Additional Information (Detail) (USD $)	1 Months Ended	12 Months Ended					12 Months Ended			12 Months Ended					12 Months Ended
	Mar. 31, 2011	Apr. 26, 2014	Apr. 27, 2013	Apr. 28, 2012	Mar. 19, 2013	Dec. 31, 2007	Apr. 26, 2014 Minimum [Member]	Apr. 26, 2014 Maximum [Member]	Apr. 26, 2014 Unearned ESOP Shares [Member]	Apr. 26, 2014 Thompson Dental Company [Member]	Apr. 27, 2013 Thompson Dental Company [Member]	Apr. 30, 2012 Thompson Dental Company [Member]	Apr. 26, 2014 1990 Note [Member]	Apr. 30, 2011 1990 Note [Member]	Apr. 26, 2014 2006 Senior Notes [Member]	Apr. 28, 2012 2006 Senior Notes [Member]	Apr. 27, 2013 2006 Senior Notes [Member]
Shareholders Equity [Line Items]
Common stock repurchased and retired, shares		2,354,000	5,224,017	11,954,257
Common stock repurchased and retired, value		$ 96,486,000	$ 181,756,000	$ 361,047,000
Average cost of common shares repurchased and retired		$ 40.99	$ 34.79	$ 30.20
Shares authorized for repurchase under share repurchase program					25,000,000	25,000,000
Remaining shares available under repurchase program		22,000,000
Shares repurchase under share repurchase program	20,500,000
Additional shares authorized for New repurchase under share repurchase program	25,000,000
Stock repurchase program, expiration date	Mar. 15, 2016
ESOP company loan													22,000,000		105,000,000
Hours of service completed in order to be allocated shares of stock acquired by plan		1000 hours
Shares secured with an aggregate cost										373,000	363,000	298,000		1,635,000	10,959,000		20,214,000
Additional loan to ESOP										12,612,000
ESOP acquiring shares during acquisition										665,978					3,159,645	844,325
Interest due from ESOP										200,000
Total shares allocated to ESOP										97,810
Remaining shares in ESOP										568,168
Contributed to ESOP																23,639
Number of shares allocated to ESOP		13,851,147
Number of shares allocated to ESOP, Fair value		566,650,000
Committed-to-be-released shares										9,197					270,117
Suspense shares										454,092					2,282,877
Unearned shares held by ESOP to occur over a period							5 years	10 years
Fair value of unearned shares by ESOP		$ 85,944,000	$ 95,124,000						$ 111,969,000