Goodwill And Other Intangible Assets (Goodwill And Related Activity) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Oct. 29, 2011
Goodwill [Line Items]
Balance at April 30, 2011	$ 795,616
Acquisition Activity	4,813
Translation And Other Activity	(1,878)
Balance at October 29, 2011	798,551
Dental Supply [Member]
Goodwill [Line Items]
Balance at April 30, 2011	132,670
Translation And Other Activity	(144)
Balance at October 29, 2011	132,526
Rehabilitation Supply [Member]
Goodwill [Line Items]
Balance at April 30, 2011	537,995
Translation And Other Activity	(1,961)
Balance at October 29, 2011	536,034
Veterinary Supply [Member]
Goodwill [Line Items]
Balance at April 30, 2011	124,951
Acquisition Activity	4,813
Translation And Other Activity	227
Balance at October 29, 2011	$ 129,991