Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Sep. 30, 2006	Apr. 25, 2020	Apr. 27, 2019	Apr. 28, 2018	Apr. 27, 2013	Dec. 31, 2002	Mar. 13, 2013	Dec. 31, 1991
Shareholders Equity [Line Items]
Common stock repurchased and retired (in shares)		0	0	2,147,000
Common stock repurchased and retired, value				$ 87,500
Average cost of common shares repurchased and retired (in usd per share)				$ 40.75
Shares authorized for repurchase under share repurchase program (in shares)							500,000,000
Remaining shares available under repurchase program (in shares)		500,000,000
Hours of service completed in order to be allocated shares of stock acquired by plan		1000 hours
Number of shares allocated to ESOP (in shares)		9,592,000
Number of shares allocated to ESOP, Fair value		$ 175,347
ESOP share based compensation expense		14,419	$ 13,740	$ 18,132
Fair value of unearned shares by ESOP		16,061	$ 50,381
Unearned ESOP Shares
Shareholders Equity [Line Items]
Fair value of unearned shares by ESOP		$ 9,319
Thompson Dental Company
Shareholders Equity [Line Items]
Additional loan to ESOP						$ 12,612
ESOP acquiring shares during acquisition (in shares)						666,000
Interest due from ESOP					$ 200
Total shares allocated to ESOP (in shares)						98,000
Remaining shares in ESOP (in shares)						568,000
Committed-to-be-released (in shares)		15,000
Suspense shares (in shares)		379,000
1990 Note
Shareholders Equity [Line Items]
ESOP company loan								$ 22,000
2006 Senior Notes
Shareholders Equity [Line Items]
ESOP company loan	$ 105,000
ESOP acquiring shares during acquisition (in shares)	3,160,000				844,000
Contributed to ESOP					$ 20,214
Committed-to-be-released (in shares)		467,000
Suspense shares (in shares)		230,000