Intangible Asset Impairment (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jan. 28, 2017	Jul. 30, 2005	Jan. 28, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Distribution fee paid		$ 100,000
Distribution relationship term extension		10 years
Distribution Rights [Member] | Dental [Member]
Finite-Lived Intangible Assets [Line Items]
Non-cash impairment charge before tax	$ 36,312		$ 36,312