Changes in Carrying Value of Goodwill (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Apr. 28, 2012
Goodwill [Line Items]
Balance at beginning of year	$ 795,616
Acquisition Activity	5,199
Other Activity	9,437
Balance at end of year	810,252
Dental Supply
Goodwill [Line Items]
Balance at beginning of year	132,670
Other Activity	7
Balance at end of year	132,677
Rehabilitation Supply
Goodwill [Line Items]
Balance at beginning of year	537,995
Acquisition Activity	304
Other Activity	4,832
Balance at end of year	543,131
Veterinary Supply
Goodwill [Line Items]
Balance at beginning of year	124,951
Acquisition Activity	4,895
Other Activity	4,598
Balance at end of year	$ 134,444